The "status of forces" accord (SOFA), a technical document tentatively approved in November after 15 months of talks, also makes possible deployments of a U.S. Patriot missile battery in Poland next year as part of plans to upgrade its air defences.

"This agreement is a good basis for cooperation between the U.S. and Polish armed forces in the future," Polish Defense Minister Bogdan Klich told reporters at the signing ceremony.

"For Poland, this signifies a strengthening of our national security."

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