LONDON -- Britain's defense ministry says the Royal Air Force (RAF) has scrambled two fighter jets as Russian planes neared U.K. airspace — another illustration of ongoing tensions. The RAF confirmed a "quick reaction alert," deploying Typhoon aircraft from the Lossiemouth base in Scotland, but military authorities say nothing was intercepted.

The incident Monday is one of several in recent years as Russian fighter planes test NATO and British air defenses.

Russia's military has also sought to probe the resolve of naval forces, with warships being diverted to monitor passing naval vessels.

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Last week, the HMS Westminster, a Portsmouth-based Type 23 frigate, was ordered to intercept two warships and two supporting vessels passing near U.K. waters.

In November, the U.S. military said a Russian fighter flew within 50 feet of a U.S. Navy reconnaissance jet over the Black Sea with full afterburners on, causing violent turbulence that knocked the American plane into a 15-degree roll.