The Lithuanian president has said she wants an ongoing US troop presence in her country in light of increased Russian activity in the region and in response to Moscow’s preparations for military exercises in neighboring Belarus late this year.

“We need the serious involvement of the US to not only deter but to defend,” President Dalia Grybauskaite told The Wall Street Journal on Tuesday, after a meeting with US Defense Secretary James Mattis. “It is important to have adequate response capabilities against possible threats.”

Planned war games by Russia and Belarus slated for September could involve up to 100,000 troops and include nuclear-weapons training. Mattis has criticized the buildup ahead of the exercise, as well as Russia’s deployment of missiles to Kaliningrad — its semi-enclave on the Baltic Sea.

“Any kind of buildup like that is simply destabilizing,” Mattis said. Moscow said the missiles were part of routine drills, but US officials worried it was a permanent upgrade to Kaliningrad’s missile capability.