OTTAWA — NATO will have to consider permanently stationing troops in parts of Eastern Europe as a result of the increased tension between Russia and Ukraine, the alliance's top military commander said on Tuesday.

NATO has arranged a number of short-term army, air force and naval rotations in Eastern Europe, including the Baltic republics, Poland and Romania, but these are due to finish at the end of this year.

Asked whether NATO might have to look at permanently stationing troops in the alliance's member states in Eastern Europe, U.S. Air Force Gen. Philip Breedlove said: "I think this is something we have to consider and we will tee this up for discussion through the leaderships of our nations to see where that leads."

NATO leaders are due to hold a summit in Wales in early September.

In the run-up to the summit, NATO commanders, defense ministers and foreign ministers would look at "tougher questions" about whether the alliance had the right footprint in Europe, Breedlove told a news conference in Ottawa.

"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," he said.

Breedlove, who said on Monday he did not think Moscow would send troops into eastern Ukraine, stressed the steps that NATO had taken so far were designed to support eastern members of the alliance.

"We are taking measures that should be very easily discerned as being defensive in nature. This is about assuring our allies, not provoking Russia, and we are communicating that at every level," he said.

Breedlove insisted the so-called U.S. strategic "pivot" toward Asia would have no effect on its commitment to NATO and collective defense, though he acknowledged that U.S. troop levels in Europe have been reduced by about three-quarters from Cold War levels.

Asked if the U.S. troop levels would be enough in light of the Russian moves, he said: "In our own country now, and I think in every other NATO nation, based on the paradigm that we see that Russia has presented in Crimea and on the border of Ukraine ... we are all going to have to reevaluate some of the decisions that have been made (after the end of the Cold War)."

Breedlove declined to say whether he thought that France should scrap the sale of two Mistral helicopter-carrier frigates to Russia, saying this was "a national decision" that was up to France. Moscow has said it would demand compensation if this took place.