David Jackson

USA TODAY

President Obama will visit Estonia early next month, and Russian aggression in Ukraine will be on the agenda.

"In light of recent developments in Ukraine, the United States has taken steps to reassure allies in Central and Eastern Europe," said Caitlin Hayden, spokesperson for the National Security Council.

Hayden said the Estonia trip "is a chance to reaffirm our ironclad commitment to Article V as the foundation of NATO," which requires mutual defense among members.

Officials in Estonia and other Baltic nations have expressed concern about Russian support for violent separatists in Ukraine, saying they could be targeted by Moscow in the future.

During his visit, Obama will meet with the presidents of all three Baltic states, Latvia and Lithuania as well as Estonia.

They will "discuss ongoing cooperation on regional security and policies that support economic growth, and to discuss collective defense," Hayden said.

Obama will travel to Estonia during the first week in September, part of a trip that includes a NATO summit in Wales -- where Russia and Ukraine will also be a major topic of discussion.