On Monday, NATO resumed its long-planned yearly nuclear drills in northwest Europe as tensions rose over the Ukraine conflict and President Vladimir Putin's warning to take all measures necessary to preserve Russian territory.
The military alliance said the drills would involve roughly 60 aircraft, including fighter jets and observation and refueling planes, from 14 of NATO's 30 member countries.
Most of the exercises will take at least 1,000 kilometers (625 miles) from Russia's borders.
