NATO's new supreme commander in Europe says the military alliance remains essential more than 25 years after the end of the Cold War.
"In today's challenging security environment, transatlantic cooperation is needed more than ever," U.S. General Curtis Scaparrotti said after taking over command from U.S. General Philip Breedlove at NATO's military headquarters in the Belgian town of Mons on May 4.
"Even with the end of the Cold War, our NATO alliance...remains vital as we face a new set of challenges," he added, identifying one of them as "a resurgent Russia, striving to project itself as a world power."
Relations between Moscow and the West have soured since Moscow annexed Crimea from Ukraine in March 2014 and shortly thereafter began backing separatists in eastern Ukraine.
"Russia has been very active in eastern Ukraine. I don't see any indication that that's going to change in the short term and I don't expect it will," Scaparrotti said.
But Moscow claims NATO is fueling tensions by bolstering its presence on the eastern fronts of the alliance.
Earlier on May 4, Russian Defense Minister Sergei Shoigu announced that Russia will set up three new military divisions in the west and the south of the country by the end of 2016.
Shoigu said the move was a response to what he called "the buildup of NATO forces in proximity to Russia's borders," as well as "intensified exercises of NATO countries."
But NATO chief Jens Stoltenberg in Mons laid the blame at Russia's feet, saying NATO's decisions were driven by Moscow's military actions in Crimea and eastern Ukraine.
"That is the reason why we have responded. It is a reaction to the behavior of a Russia which is more assertive and a Russia which has shown the will of using military force to change borders in Europe," he said.
Stoltenberg added that Scaparrotti will not only help enhance NATO's presence in the east, but also work on improving its resilience to hybrid warfare and strengthening its cyberdefenses.