North Korea issued a stern warning on Tuesday, threatening to take “responsible” military action in response to the ongoing joint military exercises between South Korea and the United States. Pyongyang claims these drills are part of an invasion plot against the reclusive nation.

The threat comes a day after South Korean and U.S. forces kicked off their annual 11-day command post training along with various field exercises. This year’s drills are expected to involve 48 field training operations, double the number from last year.

In a statement carried by state media, North Korea’s Defense Ministry “strongly denounced” the drills, accusing the U.S. and South Korea of undisguised “military threats” and “attempts at invasion” against a sovereign state.

A ministry spokesperson warned that 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.”

While no specifics were provided on the potential military action, analysts speculate North Korea could conduct missile tests or take other provocative steps to bolster its military capabilities.

South Korea’s Defense Ministry maintained the joint exercises are regular defensive training, vowing an “overwhelming response” if North Korea directly provokes the allies during the drills.

Pyongyang has long viewed such military cooperation between Seoul and Washington as rehearsals for an invasion, despite repeated assurances the drills are not aimed at the North. North Korea has previously fired missiles into the sea in response to the joint exercises.

Last week, South Korea said this year’s drills would feature live-fire, bombing, air assault and missile interception training aimed at neutralizing North Korea’s growing nuclear threats.

Concerns over Pyongyang’s nuclear ambitions have escalated as it conducted a record number of missile launches over the past two years while openly threatening preemptive nuclear strikes. The U.S. and South Korea have ramped up military collaboration and deployed strategic assets like aircraft carriers in response.

2023 has already seen North Korea conduct six rounds of missile tests and artillery drills. Leader Kim Jong Un has rejected reconciliation with the South, vowing a more aggressive military posture along disputed maritime borders.

Experts warn North Korea may stage limited provocations near the tense border this year, further escalating tensions as the U.S. and South Korea hold major elections. Pyongyang’s threatening rhetoric and potential weapons tests could intensify amid the allied military drills.