NATO announced that the alliance will deploy four multinational battalions to Estonia, Latvia, Lithuania and Poland, as tensions with Russia remain high in the wake of Moscow’s intervention in Ukraine. NATO Secretary General Jens Stoltenberg discussed the deployment at a news conference in Warsaw, Poland, prior to this week’s gathering of alliance defense ministers.

NATO’s easternmost members, including Poland and the Baltic states, have long sought the increased presence of NATO troops in their respective countries, a request driven in part by Russia’s 2014 military intervention and annexation of Crimea and because of Moscow’s backing of separatists in eastern Ukraine. The deployment has been under discussion for some time and will be formally approved at the NATO summit in Warsaw in July.

Each of the battalions is expected to consist of up to 1,000 soldiers. Germany, the UK and the U.S. are expected to lead three of the battalions, while the leadership of the fourth battalion has yet to be determined.

This month, NATO members conducted a new exercise, Anaconda-16, in Poland, an effort that included some 31,000 troops from Poland, the U.S. and 17 other NATO member nations. It’s the biggest training exercise to take place in Poland since the end of the Cold War.