Updated

Russian bombers capable of carrying nuclear weapons recently flew over waters surrounding South Korea and Japan, drawing escort planes from those two countries, a Russian defense official said.

An unspecified number of Tupolev-95MS bombers, which NATO calls “Bears,” and Russian Sukhoi-35S fighter jets were involved in the mission, but Russia’s defense ministry would not say when or why the mission took place, Reuters reported.

The Russian aircraft flew over the Pacific Ocean, Sea of Japan, Yellow Sea and East China Sea, according to the report.

Whether the Russian flyover was related to the Ulchi-Freedom Guardian exercises between the U.S. and South Korean militaries was unclear.

Russia has voiced concerns about North Korea’s nuclear weapons program and Japan's plans to deploy U.S. anti-missile technology.