The showdown between Russia and the West has evoked old Cold War tensions and was sure to dominate questions for Obama on Tuesday when he holds a joint news conference with Dutch Prime Minister Mark Rutte.
It will be Obama's first news conference since Russia made a move on Crimea.
The opportunity for Obama to seek international support came as leaders from around the world already had converged in the Netherlands for a nuclear security summit, initially the featured event at the start of Obama's weeklong, four-country trip.
But Ukraine has so far dominated Obama's side discussions with world leaders and the G-7 members. Even Russia's Lavrov, in The Hague for the nuclear summit, met on the sidelines with U.S. Secretary of State John Kerry.
Speaking earlier Monday, with Rutte at his side, Obama called Russia's annexation of the peninsula on the Black Sea a “flagrant breach of international law and we condemn its actions in the strongest possible terms.”
Obama also raised the issue with Chinese President Xi Jinping. White House aides later commended the Chinese for refusing to side with Russia, a longtime ally, on a U.N Security Council vote last week declaring the secession vote illegal. Russia, a Security Council permanent member, voted against it, while China abstained.
