President Obama and his family disappeared behind the gates of a lush oceanfront resort here on Friday afternoon to begin a weekend getaway that was in doubt until the evening before because of the tumultuous events in Crimea and Ukraine.

Deciding when a president should cancel or cut short a vacation is always a politically fraught exercise. This time, the White House’s calculation was even more complicated because Vice President Joseph R. Biden Jr. left Friday for three days in the Virgin Islands…

The White House defended Mr. Obama’s decision, saying he had kept a close eye on the Ukraine crisis all week, getting briefed and placing calls to the leaders of Russia, Germany, Britain and Japan, even as he rolled out his annual $3.9 trillion budget and traveled to New England.

“What the president will be doing this weekend in Florida is essentially what the president would be doing back at the White House,” the deputy press secretary, Josh Earnest, told reporters on Air Force One. “It’s just that the weather will be a little warmer.”