VILNIUS, Lithuania (AP) — U.S. defense officials say a long-range Patriot missile battery may be deployed to the Baltic region later this year as part of a military exercise.

If the move is finalized, it would be temporary — but signal staunch U.S. backing for Baltic nations that are worried about the threat from Russia.

U.S. Defense Secretary Jim Mattis is visiting one of the Baltic countries — Lithuania. And he's declining to confirm the specific deployment.

But Mattis says "we are here in a purely defensive stance."

U.S. officials say the Patriot surface-to-air missile system could move into the Baltic region during an air defense exercise in July. They say it would be gone by the time a large Russian military exercise begins in August and September.