A joint military exercise in which Russia and China flew nuclear-capable bombers Tuesday during President Biden’s trip to eastern Asia demonstrates how both sides remain close "even as Russia brutalizes Ukraine," a senior administration official tells Fox News. 

The drills, which the official described as the most significant cooperation between the two countries since Russia invaded Ukraine three months ago, come as Biden is in Tokyo for the Quad leaders summit with the leaders of Japan, India and Australia. 

"The exercise shows that China is continuing its military cooperation with Russia in the Indo-Pacific even as Russia brutalizes Ukraine," the official said. "It also shows that Russia will stand with China in the East and South China Seas, not with other Indo-Pacific states." 

Russia bomber joint military exercise with China

A Russian Tu-95 strategic bomber takes off during Russian-Chinese military aerial exercises to patrol the Asia-Pacific region, at an unidentified location, in this still image taken from a video released on Tuesday, May 24.  (Russian Defense Ministry/Handout/Reuters)

The bombers used in the exercise "traversed the Sea of Japan and continued through the East China Sea and the Philippine Sea," according to the official. 

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"Joint strategic bomber exercises such as this one cannot be planned quickly and was likely planned well in advance by both countries," the official also said. "To further demonstrate just how seriously China considers its military partnership with Russia, Chinese naval vessels likely participated in this joint exercise." 

Russia nuclear-capable bombers fly with Chinese aircraft over East China Sea

A Russian TU-95 bomber and Chinese H-6 bombers fly over East China Sea on Tuesday, May 24. (Joint Staff Office of the Defense Ministry of Japan/Handout/Reuters)

Russia’s Ministry of Defense, in a Telegram post, said "a group of Tu-95ms Strategic Missile Carriers of the Russian Aerospace Forces and Xian H-6 Strategic Bombers of the [Chinese] Air Force conducted air patrol over the waters of the Sea of Japan and the East China Sea." 

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Russian Tu-95 strategic bomber flies during China joint military exercise

A Russian Tu-95 strategic bomber flies during Russian-Chinese military aerial exercises to patrol the Asia-Pacific region, at an unidentified location on Tuesday, May 24. (Reuters/Russian Defense Ministry/Handout)

"The flight time of the Russian strategic missile carriers was about 13 hours," the Ministry added. "At certain stages of the route, the strategic missile carriers were escorted by F-2 of the South Korean Air Force and F-15 of the Japanese Air Force." 

Russia also said Tuesday that there were "no violations of foreign airspace."