(CNN) The world was dumbfounded by the election of Donald Trump, and his first 100 days in office have done little to alleviate a deep sense of uncertainty and unpredictability. Indeed, as one observer put it, the last few weeks alone have caused a severe case of global geostrategic whiplash.

The number of campaign promises that have morphed into presidential U-turns is staggering. Allies and adversaries alike are trying to figure out whether a Trump Doctrine is emerging, or whether, as former CIA Director Michael Hayden recently told me, a discernible doctrine does not exist in what resembles a family-run business of policy from the White House.

National security adviser H.R. McMaster "has hired a very bright woman to write the US National Security Strategy," he said. "It's a tough job. I did it twice for George H.W. Bush. But I was building on precedent and historic consensus. It's really going to be interesting to see what an America First national security strategy looks like when you've got to write it down."

Long-time American allies are comforted, though, knowing McMaster and Defense Secretary Jim Mattis make up an experienced national security team. NATO partners also welcomed Trump's declaration that he no longer considers the transatlantic military alliance obsolete.

They, along with regional allies, supported Trump enforcing the previously declared US red line in Syria against the regime's use of chemical weapons on its own people. After such an attack that the West attributed to the Syrian government earlier in the month, Trump launched retaliatory strikes.

But Asian allies, such as South Korea and Japan, are worried about US policy on North Korea. They welcome the tougher stance against Kim Jong Un's ramped up nuclear missile program, but they were rattled by the USS Carl Vinson debacle, when for a time it was unclear if the aircraft carrier was steaming towards North Korea or not. It raised the question of whether the administration really has its deterrence policy in order, and South Korea was said to feel utter confusion, even betrayal, when the carrier was actually found to be steaming away from, not towards, the Korean Peninsula.

On Iran, signals are slightly harder to read. On the one hand, the State Department again certified Iran's compliance with the 2015 nuclear deal. Yet a day later, Secretary of State Rex Tillerson strongly hinted the US could walk away from it, or try to link it to other issues it has with Iran. So far the deal remains in place and neither the EU nor the UN would agree to reimpose international sanctions on Tehran, which helped bring the country to the negotiating table.

On the Paris Climate Accord, Trump's closest advisers seem to be having an almighty tussle about whether he should stay or stray from the historic deal. Big US companies like ExxonMobil are urging the US to abide by the deal and thereby have more say at the table.

Trump has also hosted Chinese President Xi Jinping at his Mar-a-Lago estate, and seems to have reversed many of his pledges to play hardball with Beijing. But on trade, just recently a Financial Times newspaper headline blared: "Trump Fires First Protectionist Warning over steel Industry," saying this paves the way for a global showdown on steel and possible sweeping tariffs on steel imports.

In his first 100 days, President Barack Obama visited nine countries. President George W. Bush visited two. Trump has visited none. But next month he visits Brussels for a NATO summit, and Sicily, for a meeting of the G7. Whether he can convince America's allies that they have a trust-worthy friend with a strategic worldview as their most powerful ally remains to be seen, abroad and at home.

"I think I know what the policy is," Hayden told me. "I have more difficulty, Christiane, putting this policy into a broader global view. And I think that's causing unease with you, with me, and with a whole bunch of other folks who are trying to see, 'Where are the Americans going globally?'"

Afghanistan

Nick Paton Walsh

It was the mother of all statements, but he may have had nothing to do with it.

The MOAB (officially know as the GBU-43/B Massive Ordnance Air Blast) wiped out an ISIS tunnel complex in the volatile eastern part of the country last week, killing around 90 militants.

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It was the largest non-nuclear bomb used by the US in combat, but whether the new commander in chief personally approved its use is unclear.

The airstrike was immediately followed up by National Security Adviser Gen. H.R. McMaster visiting Kabul and assuring President Ashraf Ghani his country had a friend in the US and a strategic review was under way.

Yet outside of the huge bomb and its message of might, little has changed -- as the new White House is inheriting the exhaustion of both resolve and policy options of the last.

A massive troop surge? Talks with the Taliban? A lighter footprint training Afghan security forces to secure the country? All have been tried, and all have failed to stop the insurgency controlling or contesting over half Afghanistan, and the heavy-handed rise of ISIS. Add to that the intense and escalating in-fighting in the Kabul political elite, and there is a very messy summer ahead, with few decent options.

China

David McKenzie

It's arguably the world's most important bilateral relationship.

But when President Donald Trump was inaugurated back in January, several Chinese policy experts told me there was a lot of nervousness about the incoming leader.

JUST WATCHED China's delicate balance with North Korea Replay More Videos ... MUST WATCH China's delicate balance with North Korea 01:42

After all, during the campaign Trump said he would name China a currency manipulator on Day One of his term and threatened a trade war.

As President-elect, he spoke to Taiwan's president on the phone and openly questioned the 'One China' policy, a cornerstone of Washington-Beijing relations in which the US recognizes Taiwan as part of China. And Trump accused China of not doing enough to put pressure on North Korea.

100 days on? Well, it's a 180-degree shift.

In his first phone call with President Xi Jinping, Trump reaffirmed the One China policy. He has praised Beijing for taking some positive steps on the North Korea issue and he recently said that China is not manipulating its currency.

Trump denies these positions represent a flip-flop; the businessman-turned-president is saying it's all part of a deal.

"I actually told him (Xi Jinping), I said, 'You'll make a much better deal on trade if you get rid of this menace or do something about the menace of North Korea.' Because that's what it is, it's a menace right now," Trump said last week.

Trump said he has developed a strong relationship with Xi Jinping and that their scheduled 15-minute meetings at the Mar-a-Lago summit stretched into "hours."

But Yan Xuetong, a foreign policy expert at Tsinghua University, told me that the Chinese are skeptical. He said that if North Korea goes ahead with its nuclear program, then China will take the blame.

"Trump will use China as scapegoat to tell (the) American public that it is not his problem," said Yan.

In Yan's eyes, at least, the Chinese suspect more Trump policy turns.

Egypt

Ian Lee

Egyptian President Abdel Fattah el-Sisi was the first foreign leader to congratulate President Donald Trump after he won the November 2016 presidential election. The two leaders had instantly hit it off when they met a few months earlier in New York.

Their views are more aligned than were those of President Barack Obama, which reacted coolly to the 2013 coup by Egypt's military -- led at the time by Sisi. When he became president soon afterward, he ushered in a new low between Washington and Cairo.

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It was an open secret that Cairo wished for a Trump victory over Obama's former secretary of state, Hilary Clinton. Trump was perceived by Cairo as a pragmatist who had little interest in human rights.

In his first days in office, Trump invited Sisi to visit him in Washington. The Egyptian president arrived with three main objectives: deepen military cooperation, strengthen the war against terror and revive Egypt's economy. The invitation to the White House also gave the Egyptian president a legitimacy that the Obama administration had previously denied him.

Recently, in a gesture of good will and eagerness to cooperate, American Aya Hijazi was released from an Egyptian prison after Trump directly intervened to secure her release.

Expect relations to remain warm as long as Trump's administration keeps the lid on any criticism of Sisi.

Germany

Nic Robertson

German Chancellor Angela Merkel took heat from Donald Trump even before he was sworn in as president.

He accused her of making a "catastrophic mistake" on migrants, only being as trustworthy as Vladimir Putin, and intentionally trying to take business from the US.

JUST WATCHED Pence reassures NATO allies in Munich speech Replay More Videos ... MUST WATCH Pence reassures NATO allies in Munich speech 03:21

For Europeans, Trump's attitude to Merkel is symptomatic of wider issues: his like of Brexit and his dislike of the EU's single market and liberal trade values.

At the EU leaders summit in Malta this February, both French and German leaders said openly that Trump's attitude was uniting Europe to stand on its own feet.

Since then, Trump has said the EU is "wonderful" and he is "totally in favor of it." Yet he still supports Brexit and seems unaware of the instability and frustrations Europe feels because of it.

It's not the only cross-Atlantic reversal he has had. Coming into office, he said NATO was "obsolete." He told the alliance nations they need to pay their way, and has given them a deadline to promise they will.

In recent weeks Trump has changed his tune. NATO, he said, is "not obsolete" -- but he still wants members' money.

Merkel's March visit to see Trump at the White House did little to quell European concerns over his attitude to Europe, and trade in particular.

That Merkel was ignored by Trump when asking for a handshake in the Oval Office, and embarrassed by him again at the news conference that followed with an awkward comment about being spied on, reveals this relationship has some way to go before it gets on an even keel.

Iran

Frederik Pleitgen

Iran's leadership realized that Donald Trump was an unknown commodity, but many in the country's senior leadership hoped they would be able to deal with the new man in the White House.

"We hope that he will have a pragmatic approach," Iran's Deputy Oil Minister, Amir Hossein Azamaninia, told me in an interview during the transition period shortly before Trump took office. He suggested that perhaps President Donald Trump would similar to the businessman Donald Trump -- a shrewd dealmaker, whom the Islamic Republic with its oil wealth could possibly even strike deals with.

JUST WATCHED Iranians worried about US-Iran relationship Replay More Videos ... MUST WATCH Iranians worried about US-Iran relationship 02:07

But Iran soon learned that the new administration was going to take a harder line towards Tehran than President Barack Obama had. When Iran tested ballistic missiles in late January -- which the US believes could strike targets in Israel -- then-National Security Adviser Michael Flynn came down hard and fast on Tehran, announcing there would be new sanctions. He also said the US was "putting Iran on notice," without specifying what that meant.

This harsh reaction and subsequent statements by Secretary of Defense James Mattis, Secretary of State Rex Tillerson and America's UN Ambassador Nikki Haley have sowed further uncertainty in Tehran about America's strategy on Iran. The tough talk and action have put a severe damper on any notion the Rouhani administration had that its fairly constructive relations with Washington during the Obama years would continue.

At the same time, the Trump team's hard line seems to be having an effect on Iran's behavior.

There have so far been fewer reports of incidents and close encounters between US and Iranian ships in the Persian Gulf's narrow Strait of Hormuz than during the end of the Obama administration. And during Iran's National Revolution Day in February, the leadership did not display ballistic missiles as it usually has.

This has led some experts to believe that Tehran -- for all its harsh rhetoric -- is making an effort to not further antagonize an American president and Cabinet whom the Iranians view as erratic and very hostile towards the Islamic Republic.

If this was the Trump administrations intent, it could be working.

Iraq

Ben Wedeman

"I would bomb the s**t out of them," declared candidate Donald Trump, summarizing his strategy to defeat ISIS. "I would bomb those suckers ... and I'd take the oil." The crowds loved it.

A decisive victory over ISIS, plus a grand prize of a lot of cheap oil, sounds great, but the real world just doesn't work that way and slowly, perhaps, the new administration has learned this in its first 100 days.

For one thing, the battle to liberate the ISIS stronghold of Mosul, Iraq -- now into its seventh month -- has underscored just how hard it is to defeat the extremists. Since the push in the western part of the city began in February, both the US-led coalition and Iraqi forces have been bombarding ISIS as promised, using much heavier firepower than during the battle for west Mosul in the waning months of the Obama administration.

But the tactic has come at a high cost in terms of civilian casualties, brought home by what US officials concede was probably a US-led airstrike on March 17 that mistakenly killed almost 150 civilians. Hundreds of thousands of civilians are still in western Mosul, often exploited by ISIS as human shields.

But even with the heavy assault, the Trump administration is largely settling down and following the same slow, deliberate approach of the Obama administration.

The battle for Mosul has taken more than half a year and may take many more months. In neighboring Syria, there are nearly a thousand US boots on the ground, backing a mixed Kurdish-Arab force that aims at overrunning the city of Raqqa, the de facto capital of ISIS. When this will happen is anyone's guess.

And then there's that other topic Trump has toyed with: taking Iraq's oil. That was decisively shot down by Defense Secretary James Mattis, who flew to Baghdad in February and told reporters, "We're not in Iraq to seize anyone's oil."

Israel

Oren Liebermann

Donald Trump's fiery pro-Israel rhetoric during the campaign had the right and far right in Israel salivating at the prospects of a Trump administration, while Palestinians worried about an American government adopting a more hostile stance.

Trump pledged to move the US Embassy to Jerusalem, "dismantle" the Iran deal, reduce funding to the United Nations and cut aid to the Palestinians. At the same time, Trump said he wanted to close "the ultimate deal" -- a peace agreement between Israelis and Palestinians.

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Save for the last, Trump has moderated his stance and backed off his positions in his first 100 days in office. The Trump administration has said its still considering an embassy move, but has also called Israeli settlements in the West Bank unhelpful for peace and acknowledged that Iran is sticking by the terms of the nuclear deal. Some analysts in Israel have pointed out that Trump's positions on the region are beginning to resemble Obama's positions.

The Israeli right wing's fervor over Trump has cooled somewhat, but it still expects him to be a friend in the White House. From Israel's perspective, the big star of the Trump administration so far is US Ambassador to the UN Nikki Haley, who has repeatedly criticized the United Nations for focusing disproportionately on Israel. And Israeli Prime Minister Benjamin Netanyahu has repeatedly praised Trump, refusing to suggest even the slightest hint of criticism, since he entered office.

Meanwhile, a recent visit by Trump's special representative for international negotiations, Jason Greenblatt, left Palestinians cautiously optimistic that prospects weren't as grim as initially feared and that Trump was serious about attempting to restart negotiations between Israelis and Palestinians.

Palestinian President Mahmoud Abbas is scheduled to meet Trump in Washington shortly after Trump hits the 100-day mark. The meeting could be a litmus test of how the dynamic between Trump, Netanyahu and Abbas develops.

Mexico

Leyla Santiago

President Trump still has yet to meet face-to-face with Mexico's president, Enrique Pena Nieto, after an awkward encounter during the 2016 campaign. According to Mexican government officials, no plans are in the works, signaling tensions remain between the two leaders.

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Twitter exchanges, however, have cooled down since a public war of words in January between @EPN and @realDonaldTrump over payment for a wall along the US-Mexico border. Mexico still maintains it will not pay for Trump's muro (wall).

Many Mexicans still fear Trump could cut off a portion of their income, if he imposes taxes on remittances as a form of payment for the wall.

The Mexican government says, though, that its No. 1 concern is human rights violations. It has invested $50 million to expand legal services at its consulates and embassies in the US in an effort to help Mexicans fearing deportation.

Major questions also loom over the fate of the North American Free Trade Agreement. Trump has called the 23-year-old deal that allows free trade between Mexico, Canada and the US a one-sided agreement.

If a good deal is not renegotiated, Mexico plans to walk away from the pact. The uncertainty in trade relations has led Mexico to strengthen ties with other countries and explore opportunities in Asian, European and South American markets instead of the US.

After Mexico featured repeatedly in the US elections, Trump himself is now playing a role in who will become Mexico's next leader. Anti-Trump rhetoric has become a central part of Mexican campaigns heading toward the 2018 election. Leading candidates are hoping a stance against Trump will protect Mexico's interests and win over voters.

North Korea

Will Ripley

When I ask ordinary North Koreans about the impact of President Donald Trump on their lives, they give strikingly similar answers. The response is usually something like this: "It doesn't matter who the US president is. All that matters is that they discontinue America's hostile policy against my country."

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Of course, they are only repeating the same message given to them by their state-controlled media, the only media North Koreans have access to. Because US politics are not a primary focus of North Korean propaganda, the vast majority of citizens are blissfully unaware of Trump's twitter account or the cloud of controversy that has swirled around the first 100 days of his administration.

But they are aware of a few key facts. They know that Trump ordered a missile strike on a Syrian regime air base, viewed by many as an indirect threat to Pyongyang. They also know that Trump dispatched the USS Carl Vinson carrier strike group to the waters off the Korean Peninsula, albeit by an indirect route.

The reason North Koreans know these things is simple: The actions of the Trump administration play right into their government's long-standing narrative that they are under the imminent threat of attack by the 'imperialist' United States.

People have been told for their entire lives that America could drop a nuclear bomb at anytime. Citizens always voice their unanimous support of Supreme Leader Kim Jong Un. Of course, in an authoritarian country where political dissent is not tolerated, there are no opposing voices.

The North Korean government uses this 'imminent threat' to justify its substantial investment in weapons of mass destruction, even if this means citizens must sacrifice. And government officials in Pyongyang told me the policies of the Trump administration in its first 100 days only add to their sense of urgency to accelerate development of a viable intercontinental ballistic missile capable of delivering a nuclear warhead to the mainland US.

They say such a weapon is key to their survival as a nation, even as critics fear North Korea continuing down the nuclear road will only lead to further diplomatic isolation, economic hardship or worse.

There are signs that North Korea is monitoring and responding to the unpredictable rhetoric and actions of the Trump administration. After news broke that the USS Carl Vinson strike group was headed to the Korean Peninsula, I was hand-delivered a statement in Pyongyang saying, "The DPRK is ready to react to any mode of war desired by the US."

We've never seen dynamics like this before. An untested US President who tweets in real time and isn't afraid to launch missiles to prove a point. And a North Korean leader who has consolidated his power by purging opponents (including his own uncle) and has launched more missiles than his father and grandfather combined.

This could be a recipe for disaster. Or a recipe for lasting peace. Or perhaps a recipe for the continuation of a decades-long stalemate. If Trump's first 100 days provide any clues, it's going to be a wild ride regardless.

Russia

Matthew Chance

President Donald Trump entered the White House on a promise of improving the strained relationship between Washington and Moscow.

He was full of praise for his Russian counterpart, Vladimir Putin, suggesting he might recognize annexed Crimea as Russian, cooperate over international terrorism and join forces in Syria.

JUST WATCHED Lavrov to US: Respect Syrian sovereignty Replay More Videos ... MUST WATCH Lavrov to US: Respect Syrian sovereignty 01:20

It was all music to the Kremlin's ears and talk was of a pivotal moment, of the Trump administration transforming the way in which the United States and Russia saw each other.

But 100 days on, none of that has come to pass.

"One could say the level of trust on a working level, especially on the military level, has not improved," said Putin on April 12, "but rather has deteriorated."

US officials have criticized Russia for fueling conflict in Ukraine, castigated the Kremlin for its treatment of sexual minorities, even bombed Russia's Syrian ally while implying Moscow might have been complicit in dozens of agonizing deaths there caused by chemical weapons.

Part of the reason is undoubtedly the toxic political atmosphere in Washington, where lingering allegations of Russian interference in the US presidential election are being investigated by Congress.

But there is also a growing sense that the Trump administration, at 100 days old, has finally encountered a stark reality: Russia and the United States simply have different geopolitical priorities -- whether in Syria, Ukraine or elsewhere -- that won't be easily reconciled.

Syria

Clarissa Ward

When President Donald Trump first assumed office, his strategy on Syria, like much of his foreign policy, was opaque. On the campaign trail he had said that his priority was to eliminate ISIS -- indeed, he promised to put together a plan to do so in his first 30 days. He attempted to place a ban on any Syrian refugees entering the US, calling them a security threat. But on the subject of Syria's leader, Bashar al-Assad, and the brutal civil war he has presided over that has claimed more than 400,000 lives, he was noticeably silent.

JUST WATCHED Syria, a war on children? Replay More Videos ... MUST WATCH Syria, a war on children? 03:42

Trump's strong admiration for Russian President Vladimir Putin and interesting in getting the relationship with Russia back on track led many to assume that he would do little to interfere in Syria, where Moscow is closely allied with Damascus. This was reinforced by Secretary of State Rex Tillerson's comment in March that it would be "up to the Syrian people" whether or not Assad would go, a demand long made by the Obama administration. Regime change, it seemed, was no longer desirable for the US.

Yet, within a few weeks, everything changed.

After seeing the aftermath of a chemical weapons attack in Idlib that killed dozens of children, Trump suddenly took action against the Assad regime. Two days later, dozens of American tomahawk missiles rained down on the regime's Shayrat air base.

The Syrian people were stunned. Those who oppose Assad had dreamed of this moment for many years, but after President Barack Obama had chosen not to enforce his red line against Assad's use of chemical weapons in 2013, their dream had died. Suddenly, Trump was hailed as something of a hero. Some took to calling him by a new nom de guerre, Abu Ivanka al Amriki.

The strikes on Shayrat changed very little on the ground in Syria. The regime was continuing its daily bombardment within hours.

Still, after six years of standing on the sidelines, the shift in US policy (if it is a sustained shift) has given some cause for optimism. There is hope that perhaps Assad will think twice before using chemical weapons against his own people, that the US may now have more leverage at the negotiating table.

Yet the question still remains: What is the US's policy on Syria? 100 days into the Trump presidency, we still don't really know.

Turkey

Ian Lee

Relations with the Obama administration warmed under Turkish President Recep Tayyip Erdogan when that suited him and then soured accordingly. They have yet to be really tested under President Donald Trump.

Since taking office, Trump has taken a softer tone in dealing with Turkey. Ankara responded positively to the United States' missile strike on a Syrian air base. Trump congratulated the Turkish president for the success of his referendum, giving him significantly expanded powers, despite the process being deeply flawed according to international monitors, an opinion echoed by the State Department.

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By the time President Barack Obama left office, US-Turkish relations had cooled. The two leaders had differing opinions regarding Syria. Where Obama wanted to focus on defeating ISIS while Erdogan wanted to oust President Bashar al-Assad. The United States saw Syrian Kurdish militants, the YPG, as an ally against ISIS, while the Turks viewed them as terrorists. And Obama criticized Turkey's crackdown on the political opposition, intellectuals, activists and journalists and wouldn't extradite spiritual leader Fetullah Gulen, on whom the Turkish blames July's coup attempt. Elements of Erdogan's party even accused the United States of supporting the failed effort.

There is optimism in Turkey among the government and its supporters that a new page can be turned, especially when both leaders plan to meet in Washington in May.

But Trump is likely to face similar tensions as Obama did. One of the toughest will be the upcoming operation against ISIS in Raqqa, Syria. Turkey wants to take part but won't fight along side the YPG. Trump will likely have to choose between a NATO ally and a proven fighting force.

The UK

Phil Black

President Donald Trump helped create what is so far the most iconic image of Britain's Prime Minister Theresa May -- the American president holding May's hand as they walked outside the White House in January.

May later said Trump was "being a gentleman."

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She provided the opportunity for his gallantry by swiftly moving to be the first world leader to visit the new president.

May has unashamedly pursued a close bond with Trump, believing "the special relationship" between the UK and US is especially important as Britain prepares for a future outside the European Union.

May has pushed for a quick post-Brexit trade deal while also trying to persuade Trump to align with Britain's traditional positions on key foreign policy issues like NATO (crucial) and Russia (deserves suspicion).

The British Prime Minister also threw in a sweetener. She invited Trump to visit the UK with full state honors. That usually means time with the Queen, banquets, parades and gilded carriages.

Such invitations are rarely offered to new presidents and it's proved to be hugely controversial in a country where many disagree with Trump's policies, including his attempts to block immigration from select, majority-Muslim countries.

More than 1.8 million people signed a petition opposing a state visit "because it would cause embarrassment to Her Majesty the Queen." Thousands protested on the streets and have promised to do so again when Trump arrives. That could create some awkward moments.

May's efforts to stay close to Trump will likely be judged by whether she secures a free trade agreement with the United States. But they can't even begin talking about that officially until after Brexit has taken place, so that's at least two years away.