US President Barack Obama vowed boldly yesterday to degrade and destroy Isil, the radical Sunni militant movement in Syria and Iraq that said this week it had killed a second American journalist.
But then Mr Obama characteristically signalled that he will not be rushed into military action by that group, which in recent months has consumed large swathes of Syria and Iraq, or anyone else.
"Their horrific acts only unite us as a country and stiffen our resolve to take the fight against these terrorists," Mr Obama said during a one-day visit to Estonia.
"Those who make the mistake of harming Americans will learn that we will not forget, and that our reach is long and that justice will be served."
There was no detail, however, on how he would tackle Isil or how other allies might participate in any expanded military operations and, crucially, on whether these operations would extend to the launching of air strikes on its safe havens inside Syria. Mr Obama's instincts for caution and preparedness over passion and haste were on ample display.
"It's going to take time for us to be able to roll them back," he said.
"We know that if we are joined by the international community, we can continue to shrink Isil's sphere of influence, its effectiveness, its financing, its military capabilities, to the point where it's a manageable problem."
The release on Tuesday of a video of the beheading of the second journalist, Steven Sotloff, a freelance reporter, seemed timed to unsteady Mr Obama as he left Washington for Estonia where he had meant to give full attention to the crIsil in eastern Ukraine and offer security reassurances to the Baltics. It was certain also to scramble the NATO summit in Wales, which also can no longer have Ukraine as its sole focus.
Mr Obama's competence as the leader - not just of the US, but of the world - is under scrutiny as never before. At home he has been criticised even by some of his own supporters for an approach that can seem bloodless and detached. After publicly responding to the murder two weeks ago of the first journalist, James Foley, he went to play golf. Last week, he said he didn't have a strategy yet for dealing with Isil.
The portrait of a President buffeted by world events he can neither control - and seems sometimes confounded by - is also starting to trouble some of America's allies, including Britain, likely to be the first country to which it will turn when it decides what to do. "We are looking for the leader of the free world to give a lead," said one British Government minister, who asked not to be named. So far, there is nothing."
There is concern that Mr Obama's past commitment to ending the US engagement in Afghanistan and Iraq is blurring his judgement now. "I think he bears a burden with respect to the past," noted former British Foreign Secretary Jack Straw. "As much as I respect him, I think he's very long on analysis, but he's not quite as fleet of foot on being decisive - and you need a balance if you're the President of the US.""
Mr Obama's suggestion that he could turn Isil into a "manageable problem" was once again exercising his US critics. "When you hear the President talk about destroy and degrade, that makes sense. When you hear the President talking about managing the problem, that doesn't make sense," said conservative pundit Laura Ingraham said on Fox News. "This is not a manageable problem, this is a force of evil."
The two-day NATO summit is being hastily revised to discuss what further action could be taken by NATO to bolster existing operations by member states, including the supply of military equipment to Kurdish forces, humanitarian aid to besieged communities and further help on intelligence and surveillance operations. The crucial unanswered question is whether Mr Obama will ask for other member states to join air strikes.
While Mr Obama made clear he expects a coalition of states to take on Isil - he and his Secretary of State, John Kerry, will begin the task of corralling allies to the task today in Wales - there will still be pressure on him to demonstrate that at the end of the day it is he and the US that will lead it.
If the US does not mobilise and coordinate a multinational response, one is unlikely to emerge, much less be coherent, Dennis Ross, the former special advisor to Mr Obama and Middle East peace envoy, wrote in 'Politico' yesterday. Moreover, the readiness of others in the region to act overtly and covertly will depend on seeing what the US is prepared to do.