The DPRK marks the 85th anniversary of the foundation of its Korean People's Army on April 25, an important anniversary that comes at the end of major winter military drills, South Korea's Unification Ministry spokesman Lee Duk-haeng said.

South Korea said on Friday it was on heightened alert ahead of another important anniversary in the DPRK, with a large concentration of military hardware amassed on both sides of the border amid concerns about a new nuclear test by Pyongyang.

The US and South Korean officials have been saying for weeks that the North could soon stage another nuclear test in violation of United Nations sanctions, something both the United States and China have warned against.

 Top envoys from the United States, South Korea, and Japan  are due to meet on Tuesday, South Korea's foreign ministry said, to "discuss plans to rein in DPRK's additional high-strength provocations, to maximize pressure on the North, and to ensure China's constructive role in resolving the DPRK nuclear issue".

South Korea and the United States have also been conducting annual joint military exercises, which the North routinely criticizes as a prelude to invasion.

"It is a situation where a lot of exercise equipment is amassed in the DPRK and also a lot of strategic assets are situated on the Korean peninsula because of the South Korea-US military drills," Lee said at a briefing.

"We are closely watching the situation and will not be letting our guard down," Lee said.

US President Donald Trump on Thursday praised China's efforts to rein in "the menace of the DPRK", after its state media warned the United States of a "super-mighty preemptive strike".

(Source: Reuters)