BUCHAREST, Romania (AP) — NATO's deputy secretary general says Russia is conducting unannounced military exercises, straining its relationship with the Western military alliance.

Alexander Vershbow said Monday that Russia had staged large drills with no advance notification "with increasing frequency." He said there had been about a dozen in the past two years.

Vershbow, on a visit to Bucharest, said Russia's drills are allowed by a loophole in a security agreement signed with Western countries. He said NATO wants to "develop a more stringent regime to increase transparency and ...predictability and a way to better stabilize what is a very unsatisfactory relationship with Russia."

Alliance members have not staged snap drills since the end of the Cold War, he said.

NATO members Poland and Romania are uneasy about Russia's military presence near their borders.