President Barack Obama departed Washington en route to Poland, the first stop of a trip designed to reassure America’s allies in Eastern Europe.
Obama on Monday was accompanied on his presidential plane Air Force One by his national security adviser Susan Rice, senior adviser Dan Pfeiffer, and other top aides.
During the Poland leg of his four-day trip, Obama was to meet with Ukraine’s president elect Petro Poroshenko on Wednesday.
He later attends the Group of Seven summit in Brussels, where the agenda was to be dominated by Washington’s push — and Europe’s reluctance — to keep the economic screws tightened on Russia because of its seizure of Crimea.
The White House, meanwhile, announced that Vice President Joseph Biden will travel this weekend to Kiev to further bolster US bilateral ties with Ukraine.
The US leader joins the heads of state from six other major economies in Brussels on Thursday for a Group of Seven summit to which Russia was disinvited.
Obama will also visit France for talks with President Francois Hollande in Paris and for commemorations marking the 70th anniversary of the 1944 D-Day invasion in Normandy.
Obama will come face-to-face there with Russian President Vladimir Putin, in a potentially awkward encounter.
Obama has spent months trying to isolate his rival and punish the Kremlin inner circle with sanctions over Ukraine.