China called for calm and restraint on Monday, responding to planned joint drills by South Korea, the United States and Japan aimed at tracking North Korean missiles.

The planned drills, set for late next month, will be held on the sidelines of the biennial Rim of the Pacific Exercise, or RIMPAC, off Hawaii, a U.S.-led biennial multinational naval exercise.

In the latest sign of strengthening defense cooperation between South Korea, the U.S. and Japan, it will be the first time that the three nations hold three-way drills against North Korea's missile threats.

"The situation on the Korean Peninsula is still sensitive and complex," China's foreign ministry spokesman Hong Lei told reporters when asked about the planned drills by South Korea, the U.S. and Japan.

"We hope that all parties will remain cool-headed and refrain from taking actions that may escalate tensions," Hong said.

In 2014, South Korea, the U.S. and Japan signed an intelligence-gathering pact to better cope with North Korea's nuclear and missile threats.

More than 75,000 American troops are stationed in South Korea and Japan.

International sanctions against North Korea were tightened in early March after the North's fourth nuclear test in January and launch of a long-range rocket in February. (Yonhap)