North Korea on Wednesday threatened to attack the US' military bases on Guam island just hours after the American President Donald Trump raised the tone of his warnings to Pyongyang and the Pentagon sent B-1B bombers to the Korean peninsula again, a media report said.

North Korea is "now carefully examining the operational plan for making an enveloping fire at the areas around Guam with the medium-to-long-range strategic ballistic rocket Hwasong-12," a spokesperson for the Korean People's Army (KPA) said in a statement issued by the state agency KCNA.

US Andersen Air Force Base on Guam hosts the nuclear-capable B-1B strategic bombers, which were sent back by the US to the Korean peninsula on Tuesday, according to Yonhap news agency, citing South Korean military sources.

"In the morning of August 8 the air pirates of Guam again appeared in the sky above South Korea to stage a mad-cap drill simulating an actual war," the North Korean spokesperson added, accusing Washington of mobilizing strategic nuclear assets from Guam or California.

North Korea's statement was released just hours after Trump warned the Kim Jong-un regime that it "will be met with fire and fury like the world has never seen" if it does not stop threatening the US, Efe news reported.

Pyongyang's previous intimidating statements condemned the latest package of UN sanctions, implemented in the wake of the regime's weapons programs, and threatened to carry out "physical actions" against the US territory.

These latest sanctions are the most severe package approved to date, as they seek to reduce North Korean export revenues by about $1 billion (one-third of the total) a year.

The UN sanctions came as a response to North Korea's first intercontinental ballistic missile (ICBM) launch on July 4, which was a successful milestone, which was followed by a second missile launch of the same type on July 28.

Pyongyang's continued missile tests have raised tensions on the Korean peninsula and hardened the rhetoric of Donald Trump's administration, which has hinted at the possibility of pre-emptive strikes against North Korea.