PYEONGCHANG, South Korea (Reuters) - South Korean and U.S. Marines are conducting military exercises on ski slopes in sub-freezing temperatures, including shirtless hand-to-hand combat in the snow, prompting warnings of retaliation from North Korea over “madcap mid-winter” drills.

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More than 300 Marines are taking part, simulating combat on the ski slopes of Pyeongchang, host of the 2018 Winter Olympics, amid speculation North Korea could be planning another missile test in defiance of U.N. resolutions.

“U.S. Marine Corps and ROK (Republic of Korea) Marine Corps partnered together at every level to build a camaraderie and friendship of the two countries’ militaries but also to increase our proficiency in the event where we have to fight a war together,” U.S. Captain Marcus Carlstrom told reporters.

The training began on Jan. 15 and ends on Feb. 3 in Pyeongchang, about 180 km (115 miles) east of Seoul.

About 28,500 U.S. troops are stationed in South Korea in joint defense against North Korea, which is under U.N. sanctions over a series of nuclear and missile tests and which regularly threatens to destroy the South and the United States.

Poverty-stricken, reclusive North Korea and the rich, democratic South are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty.

James Mattis, in his confirmation hearing as U.S. defense secretary, described “the Pacific theater” as a priority and analysts expect new U.S. military spending under President Donald Trump to strengthen the U.S. presence in Asia.

Topping U.S. concerns in the region are North Korea’s nuclear weapons and missile programs and China’s military moves in the South China Sea.

North Korean media was dismissive of the exercises, but warned of retaliation.

“The colonial puppet forces, no more than a rabble, are keen on escalating the tension and the moves to ignite a war at a time when even their American master is at a loss how to cope with the DPRK’s powerful nuclear deterrent,” North Korea’s Minju Joson newspaper, quoted by the KCNA news agency, said.

“... If the south Korean warmongers ignite a war against the DPRK, totally counting on the U.S., the revolutionary forces of the DPRK will wipe out the aggressors to the last man by fully displaying their tremendous might ...”

DPRK stands for Democratic People’s Republic of Korea, North Korea’s official name.

Acting South Korean President Hwang Kyo-ahn said on Monday the deployment of a U.S. anti-missile defense system should not be delayed in the face of the growing North Korean nuclear missile threat. [nL4N1FD1A3]

South Korean Defense Minister Han Min-koo said on Friday North Korea’s nuclear weapons and missiles were “a direct and substantive threat” and ordered thorough military readiness, Yonhap News Agency said.