WARSAW, Poland (AP) — The presidents of Poland and of Germany are paying a visit to NATO's easternmost command center, which is being upgraded for quick reaction in the event of a threat to the alliance's eastern flank.

Andrzej Duda and Joachim Gauck are meeting on Monday with commanders and troops at the headquarters of NATO's Multinational Corps Northeast in Szczecin. Stationed there are troops from the U.S. and 24 other nations, including non-NATO countries Finland and Sweden.

Following Russia's seizure of the Crimean Peninsula in 2014, a NATO summit that year decided to raise the corps' readiness to high and to increase its force as a deterrent on the alliance's eastern flank. The corps will take command of NATO's rapid reaction force or "spearhead" in case of a threat.