The Pentagon has announced that US-South Korean war games will begin next week amid rising military tensions between Pyongyang, Seoul and Washington.

The Pentagon said in a press release that the command post maneuvers known as Ulchi-Freedom Guardian will begin Monday and run through August 31.

The Pentagon said about 17,500 American service members will participate in the drills. Last year, about 25,000 US service members joined the maneuvers.

The announcement came amid concerns that the annual military drills could spark a new crisis with North Korea which has threatened to attack the American Pacific territory of Guam.

Last week, President Donald Trump said the US would rain fire and fury on North Korea, which some interpreted as threatening the country with a preemptive nuclear attack. A day later, he doubled down on his threat saying a military option against North Korea is locked and loaded.

In response to Trump's dire warnings, North Korea said it was carefully examining a plan to strike Guam with missiles.

The North Korean military said it could carry out a pre-emptive strike if there were signs of an American provocation.

This AFP file combination of pictures shows an image US President Donald Trump (R) and North Korean leader Kim Jong-un.

On Tuesday, however, Kim Jong-un said that his country would not immediately carry out the missile attack against Guam, but warned North Korea would stay fire-ready while keeping a close eye on Washington's actions.

US Defense Secretary James Mattis warned on Monday that if a missile were to hit Guam, it would be treated as an act of war.

If they shoot at the United States, I'm assuming they hit the United States. If they do that, it's game on, he said speaking at the Pentagon.

Tensions on the Korean Peninsula escalated in July when an intercontinental ballistic missile (ICBM) capable of targeting the US mainland was successfully tested by Pyongyang.

Pyongyang says it needs its weapons as a deterrent against US expansionism and to defend its nation in the face of any US aggression.