US President Donald Trump spoke with the governor of Guam on Friday, vowing to protect the territory should the North follow through with its public plan.
U.S. officials have repeatedly said this year that military action against the North was an "option on the table" to stop North Korea's nuclear and missile programs.
And if that does not work out, then we may see further sanctions on Chinese banks and companies doing business with North Korea.
A USA nuclear expert has warned that Kim Jong-un might be coming closer to being able to produce a hydrogen bomb, also known as thermonuclear weapon, as it is able to produce tritium, a key element.
The drill coincides with the four-day "Ulji Freedom Guardian" military manoeuvres on August 21-24, which are held yearly and include joint exercises by the us and South Korean armed forces, as well as drills for emergencies. "Fight tonight" has long been the motto of US forces in South Korea to show they are always ready for combat on the Korean Peninsula.
"Gen. Dunford just arrived in Osan Air Base to meet with US Forces Korea leadership and explore the Camp Humphreys area with his team on board 2 UH-60 Black Hawks", a short statement on the Joint Staff Facebook page states. It had been known the two sides had discussions to secure the June release of an American university student.
"I'm pretty confident that the USA will protect us".
The threat came on the heels of Trump's statement that the USA would respond to North Korean aggression with "fire and fury" unlike anything the world had ever seen. Trump said. He did not specify what they might be.
Key Pyongyang ally Beijing, meanwhile, has pleaded with Trump to tone down his rhetoric to prevent tensions from boiling over. Trump played that up on Friday by retweeting a U.S. Pacific Command tweet saying the bombers on Guam are ready to fulfill their "Fight Tonight" mission if called upon. The trip has been long scheduled and was not arranged in response to the North Korean nuclear threat.
The biggest departure from North Korea's established pattern this time around was its decision to announce the details of the Guam plan.
North Korea's bold threat includes "several places they can stop or give up", said Carlin.
US diplomats aren't giving up on avoiding a military conflict. USA military options range from nothing to a full-on conventional assault by air, sea and ground forces.
North Korea's military leadership is fast approaching a self-imposed mid-August deadline to present its marshal and supreme leader, Kim Jong Un, with plans to fire missiles into the waters around the USA territory of Guam - a detailed threat of intentional provocation that has brought the region to the point of crisis.
USA forces on the island were not immediately available for comment.
The five-minute drill begins with a siren on radio, and cars are stopped at designated spots. The annual exercises, called Ulchi-Freedom Guardian, are expected to run from August 21 to 31.
"North Korea best not make any more threats to the United States. I don't see North Korea's story having any impact on tourism at this point".
While tensions typically spike around the dates of the exercises - North Korea conducted its fifth nuclear test just days after last year's maneuvers - the situation generally calms afterward as the North needs to focus on its farms and the approach of the fall harvest.
A key United States military stronghold, Guam was the departure point for US B-52 bombers that attacked Hanoi during the 1955-1975 Vietnam war.