Trump has responded with a series of bellicose statements, prompting a war of words with Pyongyang, which in turn has threatened to shoot USA bombers out of the sky and fire missiles into the waters near Guam.
The exercises came hours after a South Korean lawmaker claimed North Korean hackers had stolen a large cache of military documents from his country, "including a plan to assassinate North Korea's leader Kim Jong Un, and wartime contingency plans drawn up by the US and South Korea", reports the BBC. Two days previous to that comment the president said on the social media platform that Pyongyang had violated agreements "before the ink was dry, making fools of US negotiators".
The bilateral training mission between the U.S. B-1B bombers and South Korean F-15K fighter jets on Tuesday night followed a September 23 mission in which USA bombers and fighter escorts used pre-dawn hours to fly to the farthest point of the border between North and South Korea by any US aircraft this century.
"While I would not characterize them as the best in the world, they are among the best in the world and the best organized", Army Gen. Vincent Brooks, commander of U.S. Forces Korea, told the Senate past year.
Meanwhile, China - North Korea's closest ally and trading partner - expressed alarm at how far the rhetoric on both sides had gone, warning of the increased risk of a "fatal misjudgement"."The worldwide community won't accept North Korea as a nuclear power".
North Korea's leadership recently told Russian lawmakers that it possesses a ballistic missile with a range of 3,000 kilometers that will be able to reach US territory after modernization, the Interfax news agency reported on Tuesday.
The two B-1B bombers were accompanied by two F-15K fighters from the South Korean military after leaving their base in Guam, the South's Joint Chiefs of Staff said in a news release on Wednesday.
Reports of reconnaissance on U.S. utilities follow earlier reports alleging DPRK spies stole a large cache of military documents from South Korea, including a plan to assassinate North Korea's leader, Kim Jong-un.
North Korea expert, Lim Eul-chul, said: "It may sound insane to outsiders to fire missiles from a place he wants to develop economically, but that's how Kim runs his country".
North Korea's foreign minister has said Donald Trump "has lit the wick of a war", according to a Russian state news agency.
This May an investigative team inside the defence ministry announced the hack had been carried out by North Korea, but did not disclosed what kind of information had been taken.