At the beginning of the week, everyone in the Trump administration, from White House spokesman Sean Spicer to the ambassador to the United Nations Nikki Haley, was a realist when it came to Syria.

With the war there in its seventh year, Syrian President Bashar al-Assad was accepted as immovable and the focus was on eradicating Islamic State.

"When everything is a priority, nothing is a priority," US Secretary of State Rex Tillerson said at a Washington meeting of the coalition fighting IS. "We must continue to keep our focus on the most urgent matter at hand."

As the week ended, we found Donald Trump invoking a community of civilised nations and Haley upbraiding Russia and Iran in the style of her predecessor Samantha Power, that great proponent of the global "responsibility to protect".

The United States rediscovered its idealism. Or did it?

The realist argument was always that US blood and treasure should only be spent to prevent an IS takeover in Syria, and Washington's worst case scenario: jihadists in control of the apparatus and resources of a state.

Trump suggested after authorising this strike that the use of chemical weapons anywhere constituted a threat to US national security, though beforehand we were led to believe it was the plight of innocent people such as children that had triggered this change of policy.

Yet these children are far from the first to be brutally murdered by the Syrian regime's military machine and its Russian and Iranian reinforcements. And Trump in the past, if we are to take him at his word, did not consider even chemical attacks to warrant making the fight against Assad into America's fight.

It is hard to resist the suspicion that this is one of Trump's impulse actions, an attempt to distract from the malaise surrounding his administration or a bid to avoid embarrassment at the hands of another alpha male. Is this the kind of "shirt-front" Tony Abbott dreamt of for Vladimir Putin?

If it is indeed a captain's call, there are Middle Eastern countries that will greet it with delight. Saudi Arabia, Qatar and Turkey have all been waiting for the US to push back against Assad and his supporters, and the Sunni Muslim populations of these countries and others in the region had wondered what atrocities Assad would have to commit to persuade Washington of the humanitarian case for action.

But those fixing their bayonets to join a charge may find that when they crest the hill the Americans are nowhere to be seen. To bomb the airbase at Shayrat is, after all, a tactical strike. There has been no sign of any underlying strategy or of any input from allies, unless one counts the traditional rubber stamp of approval supplied from Canberra.

Instead, Washington's friends in Europe have sounded a note of caution, urging a multilateral approach, and are in no doubt worried Russia might respond by turning up the heat in Ukraine.

Some Arab countries, too, will not welcome Trump's attack. For Iraq, the prospect of direct conflict between the Pentagon and Iran's Revolutionary Guard not only complicates its own fight against IS but also raises the spectre of further political turmoil in Baghdad.

The Lebanese, who have only just bedded down a government in which power is shared between pro-Assad and anti-Assad elements, will also be hoping the US doesn't stay on this course for very long.

And for Egypt, any hint of regime change is an uncomfortable reminder of the freedom agenda of George W. Bush and the uncertainties of the "Arab Spring". When the US decided to invade Iraq 14 years ago, Hosni Mubarak warned Egyptian soldiers the move would create "100 Bin Ladens"; Abdel Fattah el-Sisi may well feel the same way about Syria.

If, as some of Trump's statements have suggested, it is simply a matter of curtailing the use of unconventional weapons, then Russia and Iran will soon be able to return to business as usual.

"What must follow," according to Trump's erstwhile rival Marco Rubio, "is a real and comprehensive strategy to ensure that Assad is no longer a threat to his people and to US security, and that Russia no longer has free rein to support his regime." Big words from a man the President once dismissed as little. Their meaning would seem obvious enough; having hit the regime at Shayrat, if Trump is serious about changing the dynamic he must also strike at Hmeimim and Tartus and other bases, and end the Syrian regime's control of the skies.

But without air power, there is no Assad regime. And in the absence of an Assad regime, what does the President propose? Surely the deaths of the children of Khan Sheikhoun have not turned Trump into a nation-builder.

Malcolm Turnbull has said that events in Syria cry out for a "strong response", but now, as always, we must ask whether the best strength that Washington can bring to this chaos and destruction is its military.

As Barack Obama told a graduating class at West Point in 2014: "Just because we have the best hammer it does not mean that every problem is a nail."

As for the people of Syria themselves, they want an end to war; the line that Donald Trump insists was so momentously crossed this week means little or nothing to them.

As the sign writers of the Syrian town of Kafr Nabl told a watching world in English more than 3?? bloody years ago, "if your case with Assad is only the use of CW [chemical weapons], leave him because dying by CW is far better than being bombed by Scuds".

The question now is threefold: Is Trump truly going to develop a comprehensive strategy to end the conflict in Syria? Is he going to use military means to kick away this regime, with no clear plan for Syria beyond that? Or is he like the Grand Old Duke of York, who having marched his men halfway up the hill will he now march them down again?

One thing is for certain: in all his years at The Apprentice, he never had an audience like this for his next move.