South Korea and the U.S. — which normally dismiss such threats as rhetoric — began 11 days of drills across South Korea on Monday morning to rehearse how the U.S. would deploy in time of emergency on the Korean peninsula.

The U.S. and South Korea argue the drills — which include live firing by U.S. Marines, aerial attack drills and urban warfare training — are purely defensive. North Korea claims they amount to attack preparations and has demanded they be canceled.

The North's People's Army issued a statement Monday, warning the drills created a tense situation and that its troops are "fully ready" to "blow up" the allies once the order is issued.

The North also put all its soldiers and reservists on high alert to "mercilessly crush the aggressors" should they encroach upon the North's territory even slightly, said the statement carried by the official Korean Central News Agency.

The communist country has issued similar rhetoric in the days leading up the drills. On Sunday, it said it would bolster its nuclear capability and break off dialogue with the U.S. in response to the drills.