She said: "Entering this year, the US has staged more than 80 rounds of military drills with its lackeys and those individually staged by the ROK puppets total more than 60. This evidently shows who the arch criminals straining the regional situation are.

"We will continue to build up our overwhelming and most powerful military muscle to defend our sovereignty and security and regional peace. No one can break our determination."

The same day, the North Korean Foreign Ministry spoke out against the US's criticism of its nuclear missile exercise which saw multiple rockets fired into waters off the peninsular's east coast.

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Its statement read: "[It was] a legitimate exercise of the right to self-defence to deter the outbreak of war. We resolutely oppose the US behaviour of forming exclusive military blocs and pursuing inter-camp confrontation to violate strategic security of other countries, seized by the Cold War way of thinking."

In response, South Korean President Yoon Suk Yeol told his forces to be on alert "so that North Korea does not dare challenge us at a time when the security situation is more serious than ever", according to a presidential office statement.

This comes as the US and South Korea are currently conducting their largest annual air drills together. The two-week-long set of drills involving over 100 aircraft will last until Friday.