(CNN) Afghans had only just observed a day of mourning for 103 people killed by an ambulance packed with explosives when attackers struck again, this time targeting a military base in the capital Kabul .

The attacks underline the difficulties the Trump administration faces as it reiterates Washington's security commitment in Afghanistan.

A year ago President Donald Trump spoke with US troops in Afghanistan -- hours after his inauguration. "I'm with you all the way ... we're going to do it together," he told them. It was a sentiment he repeated in condemning Saturday's attack. Gen. Joseph Votel -- who leads US Central Command and was in Kabul when the bombing occurred -- insisted "it does not impact our commitment to Afghanistan" and that victory is "absolutely" possible.

But in the past year, the Taliban has become stronger in many Afghan provinces. It now controls or contests control of at least 40% of the country, according to an official US assessment . The US relationship with Pakistan, seen by most as an essential player in Afghanistan, has deteriorated sharply. The central government in Kabul is weak and divided. It's embroiled in a struggle with a powerful provincial governor, Atta Muhammad Noor, who was fired but has refused to step down. Corruption remains endemic, especially within the national police.

And the bloodshed has continued. At least 7,000 members of the Afghan security forces have been killed in the past year. There were 2,640 civilian deaths in the first nine months of 2017, according to UN figures, though probably many more went unrecorded. Two-thirds were attributable to anti-government groups.

There have been local successes. Afghan security forces with US guidance have cleared the Taliban from a notoriously troubled part of Helmand province. But as Kosh Sadat and Stanley McChrystal, a former commander of US forces in Afghanistan, have written in Foreign Affairs , "today, Afghanistan is struggling to survive," and the Taliban's "presence and influence are likely at their highest levels since the group lost power in 2001."

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What is the US strategy?

Trump set out his Afghanistan policy in August. It involves adding US troops (from 8,400 to a level of some 13,000 now and ultimately to about 16,000), and devolving decision-making to commanders in the field. And it stressed standing up Afghan forces. "The stronger the Afghan security forces become, the less we will have to do," Trump said.

It was the opposite of what candidate Trump had promised: to get out of Afghanistan. But it was also a million miles from the ambitious counterinsurgency mission in Afghanistan set out by Gen. David Petraeus in 2010, an effort to deprive the Taliban of the conditions in which to prosper.

"We are not nation-building again. We are killing terrorists," Trump said. There was one line about the possibility "someday" of a political settlement that might involve elements of the Taliban, but the administration has not pursued such a settlement with any enthusiasm.

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The United States is not getting much help from the international community either. Allies have less than 3,000 troops on the ground in Afghanistan. In 2011, the United States and its partners had some 130,000 troops in Afghanistan. The United States is also at odds with Russia on Afghanistan (as on so much else). The top US general in Afghanistan said in April last year he was "not refuting" reports that Russia was providing weapons to the Taliban. Russia has denied providing the Taliban with arms. In turn, Russian Foreign Minister Sergey Lavrov has described the US reliance on force as a "dead end."

Lies and deceit

After the 9/11 attacks, no one heard the "with us or with the terrorists" warning uttered by President George W. Bush more loudly than Pakistan, whose military leader, Gen. Pervez Musharraf, quickly allowed the United States to use Pakistani territory to oust the Taliban.

Since then, Pakistani cooperation in the battle against extremist groups has ebbed and flowed. Rarely has the relationship been as bad as it is now. The United States has held back $255 million in military assistance. In his first tweet of 2018, President Trump said: "The United States has foolishly given Pakistan more than 33 billion dollars in aid over the last 15 years and they have given us nothing in return but lies & deceit." Pakistan's Defense Ministry shot back that after 16 years of military and intelligence cooperation, the United States has "given us nothing but invective & mistrust."

Insecurity in Afghanistan cannot be reduced if militant groups like the Taliban, al Qaeda and the Haqqani Network can use Pakistani territory as a launch pad. In the past decade, these groups have all had rear bases in Pakistan, and US officials have repeatedly accused Islamabad of turning a blind eye to, or even being complicit in, their activities -- using them as proxies to deter post-Taliban governments from getting too close to its archrival, India.

Some analysts believe the spike in violence in Kabul may be related to the bad blood between Washington and Islamabad

Over the years, Washington has tried a mix of charm, threats and cash to bring Pakistan onboard. None have worked very well. But ultimately, there is no political settlement in Afghanistan without Pakistan's cooperation. So long as the Taliban and groups like the Haqqanis can use Pakistani cities such as Quetta and Peshawar as their logistical hubs, attacks within Afghanistan will continue.

More of the same?

Between 2001 and 2017, the United States spent some $830 billion fighting the war in Afghanistan. There is no way that this administration would propose, nor the US public support, another sizeable "surge" in the US military presence in Afghanistan. Trump himself has made that clear. And there's no reason to think it would work any better than previous efforts in a country often dubbed the "graveyard of empires."

As weak and divided as the current Afghan government is, the alternative -- to Sadat and McChrystal -- is likely worse, what they term "a repressive and ideological regime that supports transnational terrorist groups." "Among a range of unpalatable choices, the best option is to pursue some version of the current policy," they write.

In other words, do enough to prevent the Taliban reaching Kabul, chip away at their strongholds, drop massive bombs on the budding ISIS contingent and painstakingly try to improve the performance of every part of the Afghan state. Little wonder that President Trump refused to attach deadlines to his strategy.