Amid signs in Washington of deep anxiety about unintended consequences and unforeseeable outcomes, President Barack Obama's appeal to Congress for support for strikes against Syria was to have its first big test today as Secretary of State John Kerry and Defence Secretary Chuck Hagel face a fierce grilling on Capitol Hill.
As aides scrambled behind the scenes to redraft a first version of an authorisation bill that has so far received short shrift from increasingly sceptical members of Congress, Obama won conditional support from two Republican hawks, Senators John McCain and Lindsey Graham, during talks at the White House.
Both warned him, however, that he would have to make a stronger case if he was to win broader congressional approval.
"We have to make it clear that a vote against this would be catastrophic in its consequences", now and in the future, McCain said afterwards.
"A degrading strike limited in scope could have a beneficial effect to the battlefield momentum. There will never be a political settlement in Syria as long as Assad is winning," Graham added.