The North American Aerospace Defense Command (NORAD) has cancelled a joint annual cooperative air defence exercise with Russia in response to the country's role in the Ukraine crisis.
Comprising the US and Canadian forces, NORAD has been conducting the Vigilant Eagle exercise with the Russian Air Force near Alaska in August or September every year since 2007.
In an email to the Fairbanks Daily News-Mine, NORAD spokesman Sergeant Charles Marsh said the US Defense Department and Canadian Prime Minister Stephen Harper suspended the exercise "due to the situation in Ukraine."
According to the spokesman, the command was already in the early planning stages of the drill when the cancellation was announced.
The Japan Self-Defense Force was supposed to attend the exercise for the first time.
Alaska Democratic Senator Mark Begich told KTUU-TV: "In order for an international exercise to be productive, there must be a level of trust among the participants.
"Unfortunately, that trust no longer exists because of Russian aggression in the Ukraine and its military's recent unprovoked buzzing of a British frigate in the Black Sea."
Vigilant Eagle 2014 was supposed to be more complex than previous exercises, involving search-and-rescue and airfield operations.
The Russian military has started large-scale snap combat readiness drills in the Eastern Military District.
The exercises were ordered by Russian President Vladimir Putin and come on the day when the European Union (EU) announced new sanctions against Moscow.
Image: A Russian Air Force Su-27 fighter intercepts a simulated hijacked aircraft entering Russian airspace at Exercise Vigilant Eagle 13. Photo: courtesy of US Air Force / photo by Tech. Sgt. Jason Robertson.