seoul, Korea - The United States and South Korea will begin their biggest combined military training in years next week in the face of an increasingly aggressive North Korea, which has been ramping up weapons tests and threats of nuclear conflict against Seoul and Washington, the South's military said Tuesday.

The allies' summertime drills, which will take place from August 22 to September 1 in South Korea under the name of Ulchi Freedom Shield, will include field exercises involving aircraft, warships, tanks and potentially tens of thousands of troops.

The drills underscore Washington and Seoul's commitment to restore large-scale training after they canceled some of their regular drills and downsized others to computer simulations in recent years to create space for diplomacy with Pyongyang and because of COVID-19 concerns.

The U.S. Department of Defense also said the U.S., South Korean and Japanese navies took part in missile warning and ballistic missile search and tracking exercises off the coast of Hawaii from August 8 to 14, which it said was aimed at furthering trilateral cooperation in face of North Korean challenges.

While the United States and South Korea describe their exercises as defensive, Ulchi Freedom Shield will almost surely draw an angry reaction from North Korea, which describes all allied trainings as invasion rehearsals and has used them to justify its nuclear weapons and missiles development.

Before they were shelved or downsized, the U.S. and South Korea held major joint exercises every spring and summer in South Korea. The spring ones had been highlighted by live-fire drills involving a broad range of land, air and sea assets and usually involved around 10,000 American and 200,000 Korean troops.

Tens of thousands of allied troops had participated in the summertime drills, which had mainly consisted of computer simulations to hone joint decision making and planning, although South Korea's military has emphasized the revival of large-scale field training this time.

Officials at Seoul's Defense Ministry and its Joint Chiefs of Staff did not comment on the number of U.S. and South Korean troops that would be participating in Ulchi Freedom Guardian Shield.

"The biggest meaning of (Ulchi Freedom Shield) is that it normalizes the South Korea-U.S. combined exercises and field training, (contributing) to the rebuilding of the South Korea-U.S. alliance and the combined defense posture," Moon Hong-sik, a Defense Ministry spokesperson, said during a briefing.

Some experts say North Korea may use the drills as an excuse to stir up tensions.

The North has already warned of a "deadly" retaliation against South Korea over its COVID-19 outbreak it dubiously claims was caused by anti-Pyongyang propaganda leaflets and other objects flown across the border by balloons launched by southern activists. There are concerns that the North Korean threat, issued last week by the powerful sister of leader Kim Jong Un, portends a provocation, which may include a nuclear or major missile test or even border skirmishes.

In an interview with Associated Press Television last month, Choe Jin, deputy director of a think tank run by Pyongyang's Foreign Ministry, said the United States and South Korea would face "unprecedented" security challenges.

Kim Jun-rak, spokesperson of South Korea's Joint Chiefs of Staff, said the South Korean and U.S. militaries were maintaining a close watch on North Korean military activities and facilities.

Animosity has built up on the Korean Peninsula since U.S.-North Korea nuclear negotiations derailed in early 2019 over exchanging the release of crippling U.S.-led sanctions against the North and the North's disarmament steps.

Kim Jong Un has since declared to bolster his nuclear deterrent in face of "gangster-like" U.S. pressure and halted all cooperation with the South. Exploiting a division in the U.N. Security Council over Russia's war on Ukraine, North Korea has dialed up weapons testing to a record pace this year, conducting more than 30 ballistic launches. They have included the country's first demonstrations of intercontinental ballistic missile technology since 2017 and further tests of tactical systems designed to be armed with small battlefield nukes.

Kim has punctuated his testing binge with repeated warnings that the North would proactively use its nuclear weapons in conflicts with South Korea and the United States, which experts say indicate an escalatory nuclear doctrine that could cause greater concerns for its neighbors.

South Korea and U.S. officials say North Korea is also gearing up for its first nuclear test since September 2017, when it claimed to have developed a thermonuclear warhead to fit on its ICBMs.