Russia and China carried out their first joint submarine patrol in the Pacific this month, according to Russian state media.

A Russian diesel-electric sub traveled about 2,000 miles from Vladivostok, operating with a Chinese vessel in the Sea of Japan and East China Sea.

While Beijing has not officially confirmed the mission, Chinese state media cited it as evidence of deepening military cooperation.

The patrol follows years of expanding joint drills, including naval patrols around Japan since 2021 and coordinated operations near Alaska, CNN has reported.

Meanwhile, the U.S. Coast Guard reported monitoring Chinese research ships in Arctic waters, and NORAD said it tracked four recent Russian surveillance flights near Alaska, an unusually high number though not considered a direct threat.