MUNICH — German leaders are pushing a vigorous new case that it is time for their nation to find a more muscular voice in foreign affairs, even suggesting that Germany should no longer reflexively avoid some military deployments, as it did in Libya almost three years ago.

Chancellor Angela Merkel has yet to weigh in on the use of the military, and it is not clear how willing the German public is to embrace a more assertive posture. But a variety of senior officials are urging a rethinking of the country’s assumptions about its diplomatic and military role. They are driven partly by alarm about crises from Ukraine to Africa, but also by unease about the strength of Germany’s partnership with the United States after revelations of American spying, and about American officials’ increasing reluctance to take the lead in interventions.

President Joachim Gauck sent the strongest signal yet of a possible change in direction with a speech late Friday at the Munich Security Conference, an annual gathering that attracts an array of world leaders and defense experts and has historically been a forum for sharp policy debates.

Germany’s Nazi and Communist pasts are no excuse for ducking international duties, Mr. Gauck said. He argued that the current Germany — “the best we have ever known,” he said — was well established as a democracy and as a reliable partner and ally, and that it should step out “earlier, more decisively and more substantially” on the world stage.