An aircraft flies through dense clouds under the setting sun. Photo:China Military

The sixth joint aerial strategic patrol by the Chinese and Russian militaries was extended to a second day over the West Pacific on Wednesday, marking the first time such an operation was carried out in two phases in two directions, as China-Russia military cooperation continues to deepen, experts said.

The militaries of China and Russia wrapped up the second phase mission of the sixth joint aerial strategic patrol above the western waters of the Pacific Ocean on Wednesday, China's Ministry of National Defense said in a press release.

Based on an annual cooperation schedule between the two militaries, the joint patrol was launched on Tuesday, with two Chinese H-6K bombers and two Russian Tu-95 bombers covering areas over the Sea of Japan and the East China Sea, escorted by fighter jets.

The previous five joint aerial strategic patrols, which were held since 2019, were all carried out within a single day, observers said.

By holding the joint patrol in two phases in two different directions, the operation has become more challenging and demanding in terms of operation planning and the rendezvous of aircraft, Fu Qianshao, a Chinese military aviation expert, told the Global Times on Wednesday.

It requires Chinese and Russian forces to practice constantly to cooperate perfectly, given that the two countries fly different aircraft and use different navigation and control systems, and the operations are being carried out over the far sea, Fu said.

Chinese military expert and TV commentator Song Zhongping told the Global Times on Wednesday that the two phases might feature different missions.

The mission objectives in the Sea of Japan and the East China Sea are likely different from those in the West Pacific, Song said.

The extended patrol displayed the ever-deepening military cooperation between China and Russia, which is very important to safeguarding of peace and stability in the Asia-Pacific region, both experts said.

Observers pointed out that the air patrol was likely accompanied by naval forces, as Japan's Ministry of Defense Joint Staff said in a press release on Tuesday that Japan spotted a Chinese warship flotilla consisting of a Type 052D destroyer and a Type 054A frigate when they sailed from the East China Sea through the Miyako Strait into the West Pacific on the day.

The China-Russia joint strategic patrols are becoming more realistic and combat-oriented, as the two countries are ready to operate together in case emergencies occur, analysts said.

Tension has been rising in the Asia-Pacific region recently, with the US seizing every opportunity to provoke China, including by sending warships and warplanes to the Taiwan Straits and the South China Sea, rallying allies in the region like Japan and the Philippines, and selling weapons to the island of Taiwan.

Given this situation, military cooperation between China and Russia can offset the US' hegemonic moves and contribute to regional peace and stability, experts said.