March 16 (UPI) -- North Korea claimed Thursday the United States deployed a supersonic U.S. bomber during joint training exercises on the peninsula.
Pyongyang's state-controlled news agency KCNA stated the "U.S. imperialists and their hunting dogs" are "deepening the threat of nuclear weapons."
"Nuclear threats are being stepped up," Pyongyang said.
In the statement, North Korea claimed the U.S. B-1B bomber departed Andersen Air Force Base in Guam on Wednesday, and the move was unilateral.
"For about an hour, the United States conducted atomic bombing exercises that rehearsed pre-emptive strikes against our major facilities," North Korea stated.
The United States and South Korea recently completed missile-warning drills, South Korean news service News 1 reported.
"The act of pre-emptive strike against us demonstrate the reckless militarization of the enemies," the statement from KCNA read. "Despite our repeated warnings, as [the enemies] make a frantic last-ditch effort to engage in a scheme of provocation, we will mete out more ruthless nuclear punishment."
South Korea's defense ministry spokesman Moon Sang-kyun neither denied nor confirmed whether the B-1B bomber allegations were true.
"For reasons of operational security, we cannot give confirmation on this matter," Moon said Thursday.
Joint U.S.-South Korea exercises began March 1 are expected to continue for two months.