– President Obama will leave Tuesday for a four-nation trip to Asia, looking to recharge a focus on the region, an ambitious initiative that’s been sidetracked by domestic politics and international conflicts elsewhere.

Yet even as Obama attempts to boost his effort to emphasize U.S. interest in Asia, Russian President Vladimir Putin’s intervention in Ukraine is complicating efforts to reassure Asian nations — which share the region with an increasingly assertive China — that the United States is committed to their security.

The administration’s efforts to refocus U.S. policy toward Asia were already being questioned in the region with the departure of Secretary of State Hillary Rodham Clinton, who made Asia her first official overseas destination in 2009, and worries that a tight U.S. budget and continuing turmoil in the Middle East were proving too distracting for the administration.

Obama added to those ­worries last fall when he scrapped plans to attend two summits in Asia because of the federal government budget shutdown. Two of the stops on this week’s trip — Malaysia, where he’ll be the first U.S. president to visit since Lyndon Johnson, and the Philippines — had been on his itinerary last fall. He’ll start the trip with visits to U.S. allies Japan and South Korea.

Asia watchers said there was fear that the United States didn’t have the staying power and that it wouldn’t have the money to back up its claims of commitments to boost economic, security and diplomatic ties with Asia.

“In polite company people won’t say it, but behind closed doors I think they’ll openly ask where the pivot is. They don’t know where it is,” said Victor Cha, a senior adviser and Korea chair at the Center for Strategic and International Studies, a Washington research center.

Russia’s apparent success at slicing off Ukraine’s Crimea region without paying a significant cost is raising fears about whether the United States would be reluctant to act if nations in the region faced ­similar aggression from neighboring countries.

The trip comes as tensions in the region have mounted, with China rattling its neighbors in November by aggressively expanding its airspace to include contested waters between China and Japan.

Regional fears include North Korea’s bellicosity and the possibility that it “could seize a couple of islands in the West Sea and see if it can pull off its own fait accompli,” Cha said. “Having the president in the region, sending strong messages … and talking with all the allies, I think helps to shape the strategic environment in which nobody comes up with crazy ideas like this” in Asia.

The Ukraine crisis, too, comes on the heels of Obama’s decision last fall to consult with Congress on a possible military strike against Syria, whose regime has been widely blamed for a chemical weapons attack.