North Korea threatened on Tuesday to take unspecified “responsible” military action in response to the ongoing joint military drills between South Korea and the U.S., drills North Korea claims are part of an invasion plot.

The North’s warning came a day after South Korean and U.S. forces began their annual computer-simulated command post training and a variety of field exercises for an 11-day run. The drills this year are expected to feature 48 field exercises, twice as many as last year.

In a statement published by state media, the North’s Defense Ministry said it “strongly denounces the reckless military drills of the U.S. and [South Korea] for getting more undisguised in their military threat to a sovereign state and attempt for invading it.”

A ministry spokesperson said the North’s military will “continue to watch the adventurist acts of the enemies and conduct responsible military activities to strongly control the unstable security environment on the Korean Peninsula.”

Leader Kim Jong Un said the North would not seek reconciliation with the South and he would eliminate the country’s long-standing goal of peaceful reunification. (Korean Central News Agency/Korea News Service via AP)

Concerns about the North’s nuclear program have grown in the past two years, as it has test-launched missiles at a record pace and openly threatened to preemptively use nuclear weapons. In response, the South and the U.S. have expanded their military exercises and increased the deployment of powerful U.S. military assets, including aircraft carriers and nuclear-capable bombers.

This year, the North performed six rounds of missile tests and artillery firing drills.

Leader Kim Jong Un said the North would not seek reconciliation with the South and that he would eliminate the country’s long-running goal of peaceful unification with the South. Kim also said the North would take a more aggressive military position along the disputed sea boundary with the South.

The North is expected to further dial up tensions with more missile tests and warlike rhetoric this year as the South and the U.S. hold major elections. The North may stage limited provocation near the tense border with South Korea this year, according to experts.

The Associated Press contributed to this report.