A simple sentence to describe a complicated situation:

"Iran made a very big mistake!"

Amid already escalating tensions between the US and Iran, Donald Trump tweeted his response to a US Navy drone being shot down by Iran.

The US was quick to say the drone was in international airspace. The Iranians say it was clearly in their territory.

After weeks of threats, counter-threats, accusations and aggravations, Iran now says: "We do not have any intention for war with any country, but we are fully ready for war."

And the US…?

Naturally, Mr Trump answered that question with a coy line readymade for cable news straps: "You'll soon find out."

By noon, he had expanded on his tweet. Sitting in the Oval Office during a meeting with Canadian Prime Minister Justin Trudeau he suggested that someone literally may have shot the drone by mistake.

"I find it hard to believe it was intentional to tell you the truth," he said. "It was probably someone loose and stupid."

Perhaps he was giving himself, and Iran, some room to move.

The US Department of Defence released the map on the left showing where they say the drone was shot down. Iran's Foreign Minister tweeted the map on the right. ( AP/Twitter )

He added that had the drone been manned, that would have made a "big, big difference."

And yet he ended his comments by saying: "This is a new wrinkle. A new fly in the ointment. And this country will not stand for it."

So you got the conclusion there, right?

Yeah, me neither.

It's possible that the President is undecided on his next move, buying time publicly as he dukes it out with his advisers backstage.

Trump has campaign promises to consider

Mr Trump said he did not think Iran's actions were intentional during a meeting with Canadian Prime Minister Justin Trudeau in the Oval Office. ( AP: Evan Vucci )

Mr Trump's re-election campaign has been front and centre this week as he formally announced his candidacy. Ending conflicts in the Middle East was one of the promises he made on the trail in 2016.

Since then, he's been vocal about not wanting a war, even as he's ordered 2,500 troops to the region.

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But conversely, Iran has been in the President's sights since the beginning.

Ending US involvement in the Obama-era Iran Nuclear Deal was a key campaign promise, one that he fulfilled last year.

Having come to office with an anti-Iran stance, the President partially brought this current conflict on himself. The administration replaced the nuclear deal with sanctions, and, some would say, has pushed Iran so hard with its rhetoric that Tehran has no choice but to respond in kind.

Some of the President's Republican allies feel that inaction can make a President and his country look weak. The White House called an emergency meeting with congressional leaders after the news broke today.

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"I'm confident if there's a war with Iran they lose. I'm confident it would be very devastating to the region. It will not be pretty. I don't want to go there, but what more do you want the President to do?" Republican senator Lindsey Graham said.

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That sentiment is trumpeted by a few hawkish voices on Mr Trump's staff.

His National Security Adviser, John Bolton, has been pushing for war for years. In May, he declared that "any attack on United States interests or on those of our allies will be met with unrelenting force".

Mr Trump's Secretary of State, Mike Pompeo, has been talking up a relationship between Iran and Al Qaeda as Congress listens with a sceptical ear. The point is that such a relationship could give the administration the authority to invade Iran under the 2001 Authorisation of Force Act.

Yep, that's the same piece of legislation that allowed then-president George W Bush to retaliate for 9/11. The Democrat-controlled House voted to repeal the bill last week in an attempt to return powers of war to Congress, but the Republican-held Senate is unlikely to agree.

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Meanwhile, Acting Defence Secretary Patrick Shanahan has directed troops to Iran as a "prudent repositioning of assets in response to indications of a credible threat by Iranian regime forces."

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Oh, and speaking of Mr Shanahan. He announced this week that he's leaving the administration rather than stepping into the role full-time. He can't go through with the nomination process because of a disturbing past with family violence.

Awful timing, and an even more awful backstory.

'Friends of America view Washington as the problem'

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 17 seconds 17 s The attacks left one tanker on fire and all sailors were evacuated from both ships

Later in the day, the Pentagon held a press conference featuring a phone call from Lieutenant General Joseph T Guastella of US Central Command at a base in Qatar.

He characterised Iran's move as "an unprovoked attack on a US Surveillance asset that had not violated Iranian airspace at any time during its mission" and called the Iranians' comments "categorically false".

The department took no questions, and shared as evidence a map that looked more like your phone's GPS app than a military document, illustrating the drone as a dot over the Strait of Hormuz. There was no flight path.

The Defence Department later released a seconds-long, low-quality video of a smoke trail of the drone.

It's hardly the clear evidence that America's allies will be looking for.

Leaders in the UK, Germany and Japan initially asked for more evidence after the US blamed Iran for two attacks on two oil tankers in the Gulf of Oman last week.

The Trump administration has little trust banked with allies in Asia and Europe. As one Washington Post columnist put it, "foreign capitals seemed more scared of the threat posed by Trump than Iran to peace and stability in the Gulf".

"A President who has repeatedly insulted major allies and denounced US intelligence agencies is finding that his words have devalued what should be America's best weapons for containing Iran," David Ignatius wrote.

"Incredibly, given Iranian intransigence and meddling in the region, many traditional friends of America view Washington as the problem these days."

The United Kingdom, Germany and Canada have all recently come out on the side of the Americans, saying they believe Iran was responsible for the oil tanker attacks.

In pushing back against Iran's behaviour, world leaders have perhaps forgotten the collective intake of breath when Mr Trump unilaterally withdrew from the nuclear deal. The collective wisdom was that Iran was adhering to its conditions, and that a form of the deal was better than no deal at all.

There is also the suggestion that in the current context, the administration is overstepping its stated aim, which is simply to prevent Iran from making nuclear weapons.

This drama with the allies leaves Mr Trump with few options. And after all, what are they?

Conduct a surgical strike on Iranian assets. Ignore Iran's niggling and hope it goes away. Or find a way of opening dialogue to de-escalate the situation.

Unfortunately, the latter seems to be the least likely option.