North Korea warns of 'merciless strike' ahead of US-South Korea drills

North Korea warned Sunday that the upcoming US-South Korea military exercises are "reckless behavior driving the situation into the uncontrollable phase of a nuclear war, " CNN reported.

Pyongyang also declared that its army can target the United States anytime, and neither Guam, Hawaii nor the US mainland can "dodge the merciless strike."

The messages in Rodong Sinmun, the official government newspaper, come a day before the US starts the Ulchi Freedom Guardian military exercises with South Korea.

Tensions between the US and North Korea have grown in recent weeks.

Just last week, Pyongyang said it had finalized a plan to fire four missiles toward the US territory of Guam. State media reported that leader Kim Jong Un would assess the US' next move before giving launch orders.

Kim would "watch a little more the foolish and stupid conduct of the Yankees," a North Korean statement said last week.

But US military and Trump administration officials said the 10-day military exercises set to begin Monday, would go ahead as scheduled.

The annual drills antagonize Pyongyang, which sees them as practice for an invasion. However, the US and South Korea maintain they are purely defensive.

"The Trump group's declaration of the reckless nuclear war exercises against the DPRK ... is a reckless behavior driving the situation into the uncontrollable phase of a nuclear war," Rodong Sinmun said, using the acronym for Democratic People's Republic of Korea, the nation's official name.

It described North Korea as the "strongest possessor" of intercontinental ballistic missiles capable of striking the US mainland from anywhere.

"The Korean People's Army is keeping a high alert, fully ready to contain the enemies. It will take resolute steps the moment even a slight sign of the preventive war is spotted," it said.

It did not provide any details on what it meant by "preventive war."