With a bitter power struggle intensifying between Iran and Saudi Arabia and widening crises in Syria, Iraq, Libya and Egypt, Washington’s relative lack of influence and involvement has become a diplomatic problem and may be contributing to a growing threat from Islamic extremists, diplomats say.

Senior officials in Saudi Arabia, Turkey and Israel all have complained about what they view as an American retrenchment after the wars in Iraq and Afghanistan, with some leaders already beginning to chart policies more independent of Washington than in the past.

Secretary of State John F. Kerry sought to ease those concerns Friday, insisting in a foreign policy address during the World Economic Forum in Davos, Switzerland, that “it is a myth that we are pulling back or giving up or standing down…. Nothing could be further from the truth.”…

“There are people who would love to see America fight their war for them,” Kerry said. “But that is not their choice.”