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Two Russian warplanes edged near the USS Ronald Reagan aircraft carrier in the Sea of Japan this week — forcing the Navy to send U.S. fighter jets in response, military officials said Thursday.

A U.S. Navy F/A-18 Super Hornet fighter lands onto the deck of the USS Ronald Reagan, a Nimitz-class nuclear-powered super carrier, during a joint naval drill between South Korea and the U.S. in the West Sea, South Korea, on Oct. 28, 2015. Kim Hong-ji / AP

The American aircraft carrier was in international waters east of the Korean peninsula in a joint exercise with South Korean naval forces.

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The pair of Russian Bear Bombers had failed to respond to radio calls as they advanced toward the vicinity of the USS Ronald Reagan, and four F/A-18 Super Hornets were deployed, U.S. Navy officials said. Once under American escort, the Russian bombers skimmed the water at an altitude of 500 feet and came within one nautical mile of the aircraft carrier.

Navy officials said such encounters in that region are not unprecedented, and the intercept and interaction were considered "safe."

Russia has routinely tried to test international boundaries over the past few years by sending warplanes near other countries' airspace — or violating their airspace altogether.

On July 4, the Russians sent planes near Alaska and California, coming perilously close to U.S. airspace without entering it.

In addition, some warplanes were sent to circle U.S. Navy ships in the Black Sea during Russia's takeover of Crimea. U.S. officials have labeled these as "provocative actions."