NATO’s troop build-up in Eastern Europe amid tensions with Russia over Ukraine could become permanent, the military alliance’s top general said Tuesday.

NATO countries drew down their defense budgets following the end of the Cold War, as they started to look upon Russia as a partner, US General Philip Breedlove said.

But Russia’s “annexation of Crimea… changes that dynamic,” the NATO Supreme Allied Commander in Europe told a press conference, after meeting with Canada’s Prime Minister Stephen Harper and other officials in Ottawa.

“What we are very clear about now is that that paradigm has changed in the current situation; Russia is not acting as a partner,” Breedlove said.

“I think we need to look at our responsiveness, our readiness, and then our positioning of forces to be able to address this new paradigm that we have seen demonstrated in Crimea and now on the eastern border of Ukraine.”

Pressed about whether the situation in Ukraine could result in a permanently beefed up NATO military presence in allied countries bordering Russia, he said: “I think this is something that we have to consider.”

But that decision, he added, will be made by NATO leaders at an upcoming summit, where they will look into the question of whether they are correctly positioned in Europe.

The 28 members of the North Atlantic Treaty Organization have responded to Russia’s intervention in Ukraine by stepping up defenses in Eastern Europe, sending warships, fighter jets and troops to the region.

The troop surge is scheduled to end on December 31.