China and Russia have started joint naval drills in the waters near the Russia-North Korea border.
On Monday, off Russia's southeastern port of Vladivostok, are the second part of China and Russia's 'Joint Sea-2017' programme that started in June. 
The drills, which include submarine rescue and anti-submarine exercises, are not directly linked to increasing tensions over North Korea, China's state-owned Xinhua news agency reported.
The exercises are taking place in the Sea of Japan and, for the first time, the Okhotsk Sea.
South Korea and the United States also staged military drills in the Korean Peninsula on Monday, conducting bombing exercises involving six US planes and four South Korean fighter jets, according to Song Young-moo, the South Korean defence minister.
The UN Security Council (UNSC) voted unanimously to Impose fresh sanctions on North Korea last week after a meeting on September 11 in response to the crisis.
Pyongyang has claimed the measures - including a ban on textiles and a cap on oil supplies - will speed up North Korea's nuclear weapons programme.
"The increased moves of the US and its vassal forces to impose sanctions and pressure on the DPRK will only increase our pace towards the ultimate completion of the state nuclear force," a statement on North Korean state media said on Monday, using the acronym for the country's official name, the Democratic People's Republic of Korea.