More than 2,000 troops from nine NATO nations are on the march in Poland, participating in the first exercise of NATO's new rapid response force. Alliance leaders say the exercises are intended to reassure eastern European member-countries rattled by Russia's role in the Ukraine crisis.
NATO chief Jens Stoltenberg joined reporters Thursday in western Poland, where they witnessed an hour-long display of live firepower from Polish, Czech and Lithuanian special forces. U.S. and Polish fighter jets and German armor also participated.
Ahead of the demonstration, Stoltenberg told Germany's Bild newspaper that the drills send "a clear signal that our alliance is prepared, willing and able to cope with all challenges lying ahead of us."
Stoltenberg also criticized Russia's "aggressive actions" in Ukraine, where pro-Russian separatists are battling Ukraine forces for control of the country's Russian-speaking east.
"Russia supports the separatists with training, weapons and soldiers," he said. He repeated recent assertions that Moscow's backing includes more than 1,000 tanks, artillery and air defense systems.
Stoltenberg described Russian President Vladimir Putin's threat this week to counter NATO by boosting his country's nuclear arsenal as "saber rattling" that "destabilizes the situation and is very dangerous."
The Kremlin routinely denies providing Ukrainian rebels with troops or hardware, and says Russian soldiers seen or captured in Ukraine are there as volunteers.
Speaking alongside Stoltenberg Thursday, Polish Defense Minister Tomasz Siemoniak told the French news agency that Europe's extended period of post-Cold War peace is "now over." He linked his comments to an array of crises facing Europe, including Ukraine, the growing threat from Islamist extremists and instability in North Africa.