MOSCOW, Aug 27 (Aljazeera) - Vessels from the Russian Navy returned from more than three weeks of joint-patrolling the Pacific Ocean with Chinese warships – manoeuvres that came close to the US West Coast.

Warships of Russia’s Pacific Fleet, together with a detachment of Chinese navy ships, travelled more than 7,000 nautical miles (13,000km) through the Sea of Japan, the Sea of Okhotsk, the Bering Sea, and the Pacific Ocean, Interfax news agency reported on Sunday.

During the patrol, the Russian-Chinese detachment passed along the northern Japanese island of Hokkaido – an area known in Russia as the Kurils and in Japan as the Northern Territories, which has been at the core of decades of tension between the neighbours.

The Russian-Chinese warships also circled part of the Aleutian Islands archipelago. Most of the Aleutian Islands belong to the US state of Alaska, but the Commander Islands near the Kamchatka Peninsula are part of Russia.

The Wall Street Journal reported in early August that 11 Russian and Chinese ships steamed close to the Aleutian Islands, in what appeared to be the largest such flotilla to approach US shores.

The ships never entered US territorial waters, the newspaper reported, citing US officials.

Some of the Russian Pacific Fleet’s largest warships participated in the exercise, Interfax reported.

“During the patrol, joint anti-submarine and anti-aircraft exercises were carried out. A search was made for submarines of a mock enemy using helicopters and aircraft of naval aviation from both sides. Mock missile firing was carried out at a detachment of mock enemy ships,” the news agency said.

In September, China sent more than 2,000 troops along with 300 military vehicles, 21 combat aircraft, and three warships to take part in a sweeping joint exercise with Russia.

The Vostok 2022 (East 2022) exercise took place in various locations in Russia’s Far East and the Sea of Japan and involved more than 50,000 troops and 5,000 weapons units – including 140 aircraft and 60 warships, according to the Russian defence ministry.