WASHINGTON — President Obama will travel to Estonia during the first week of September to reassure Baltic allies that they have the support of the United States, the White House said, as tensions rise over Russian intervention in Ukraine.

Mr. Obama is adding the stop in Tallinn, the capital of Estonia, to his scheduled trip to Wales for a NATO summit meeting, where the crisis in Ukraine is expected to be one of the main topics of discussion.

The White House said the stop would include meetings with President Toomas Hendrik Ilves of Estonia, President Andris Berzins of Latvia and President Dalia Grybauskaite of Lithuania.

“In light of recent developments in Ukraine, the United States has taken steps to reassure allies in Central and Eastern Europe, and this trip is a chance to reaffirm our ironclad commitment to Article V as the foundation of NATO,” Caitlin Hayden, a spokeswoman for the National Security Council, said in a statement.