North Korea is reportedly engaged in a large-scale live-fire artillery exercise, in what is apparently intended to signal to a hostile United States that Pyongyang is combat-ready.

On Tuesday, South Korea’s Yonhap news agency reported that the North appeared to have deployed a large number of long-range artillery units in the region of Wonsan on its east coast for the drill.

The day coincides with the anniversary of the establishment of the North’s military. The United States, North Korea’s archenemy, and regional adversaries South Korea and Japan have harbored fears that the occasion might witness another nuclear test by Pyongyang.

North Korea has so far conducted five confirmed nuclear tests and numerous missile test-launches. Pyongyang has also vowed strong action, including a nuclear strike, if it is invaded by the South and the US.

The North faces international pressure to abandon its arms development and nuclear military programs, which it says are meant to protect the country from US hostility.

Pyongyang and Washington have been issuing increasingly gruff threats against one another in recent weeks.