B-52 Stratofortress bombers began arriving Tuesday at Andersen Air Force Base in Guam, temporarily providing the Pentagon with a rarity as tensions with North Korea percolate: the presence of three kinds of bombers in the Pacific.

The six B-52s and 300 airmen from Barksdale Air Force Base in Louisiana will take over the U.S. military’s “continuous bomber presence” mission in the Pacific from a unit of B-1B Lancer bombers at the end of the month, Air Force officials said in a news release. The mission, which has existed since 2004, is designed to reassure U.S. allies in the region and show strength against China, North Korea and other potential adversaries.

The B-52s and B-1s will be joined in Guam by three B-2 Spirit stealth bombers, which deployed last week from Whiteman Air Force Base in Missouri. The bat-winged bomber arrived in what the Pentagon characterized as a short-term deployment, giving the Pentagon an unusually robust show of force this month in Guam until the B-1s return to Ellsworth Air Force Base in South Dakota. The Pentagon last had three kinds of bombers deployed in the Pacific in 2016.

The deployments could have additional significance in the Pacific considering the planes’ capabilities. The B-2 is the only U.S. bomber capable of carrying a nuclear gravity bomb. B-52s are able to carry smaller nuclear cruise missiles, while B-1s do not carry nuclear weapons as a result of a the 2010 New START Treaty between the United States and Russia.

The deployment of the B-52s in the Pacific came at the same time that the Pentagon sent four other B-52s from Minot Air Force Base in North Dakota to Britain. They will carry out training from the base RAF Fairford, reassuring allies in Europe.

Last week, Marine Lt. Gen. Kenneth F. McKenzie Jr., the director of the Pentagon’s Joint Staff, told reporters at the Pentagon that it would be wrong to view the deployment of the B-2s “within the single lens of what it means to the Korean Peninsula.” It affects allies across the Pacific, he said.

But McKenzie acknowledged that when the Pentagon moves bombers across the globe,”we send a signal to everyone.”

The B-1s have been involved in numerous shows of force against North Korea in the past few months, sometimes flying in formation with other aircraft from the United States, South Korea and Japan before dropping bombs on training ranges in South Korea.

North Korea’s foreign minister, Ri Yong Ho, threatened in September to shoot down U.S. warplanes, even if they are not in North Korean airspace. He argued that President Trump’s tweets about the standoff between the two nations was tantamount to a declaration of war. U.S. officials said afterward that they would continue to use international airspace for missions.

The verbal sparring has continued on both sides. On Tuesday, North Korea’s official news agency called a recent tweet by Trump the “spasm of a lunatic.” The accusation referenced Trump’s Jan. 2 suggestion that he had a “Nuclear Button” that was “much bigger & more powerful” than that of North Korean leader Kim Jong Un.

Trump’s tweet came after Kim warned the United States not to test him in a Jan. 1 address.

“The United States can never fight a war against me and our state,” Kim said in the nationally televised speech. “It should properly know that the whole territory of the U.S. is within the range of our nuclear strike and a nuclear button is always on the desk of my office, and this is just a reality, not a threat.”

Simon Denyer contributed to this report.