WARSAW, Poland (AP) — The leaders of nine NATO members on the alliance's eastern flank have reaffirmed their intention to cooperate more to increase their security in light of what they called an "aggressive" Russia that threatens their vision of a free and peaceful Europe.

Eight presidents and one parliament speaker held the third meeting of the Bucharest Nine, a group of nations once under the control of the Soviet Union. They created the forum after Russia annexed the Crimean Peninsula from Ukraine in 2014 and began supporting pro-Russia rebels in Ukraine's east.

In a declaration Friday they cited Russia's build-up of conventional forces, hybrid warfare and the nerve agent attack on a former Russian spy in England, which they said "threaten our long-standing vision of a Europe whole, free and at peace."