The United States and South Korean troops kicked off their annual drills yesterday that come after President Donald Trump and North Korea exchanged warlike rhetoric in the wake of the North's two intercontinental ballistic missile tests last month.

The Ulchi Freedom Guardian drills are largely computer-simulated war games held every summer and have drawn furious responses from North Korea, which views them as an invasion rehearsal. Pyongyang's state media on Sunday called this year's drills a "reckless" move that could trigger the "uncontrollable phase of a nuclear war."

Despite the threat, U.S. and South Korean militaries launched this year's 11-day training yesterday morning as scheduled. The exercise involves 17,500 American troops and 50,000 South Korean soldiers, according to the U.S. military command in South Korea and Seoul's Defense Ministry.

No field training like live-fire exercises or tank maneuvering is involved in the Ulchi drills, in which alliance officers sit at computers to practice how they engage in battles and hone their decision-making capabilities. The allies have said the drills are defensive in nature.

South Korea's President Moon Jae-in said that North Korea must not use the drills as a pretext to launch fresh provocation, saying the training is held regularly because of repeated provocations by North Korea.

North Korea typically responds to South Korea-U.S. military exercises with weapons tests and a string of belligerent rhetoric. During last year's Ulchi drills, North Korea test-fired a submarine-launched ballistic missile that flew about 500 kilometers (310 miles) in the longest flight by that type of weapon. Days after the drills, the North carried out its fifth and biggest nuclear test to date.

In an editorial published Sunday, official North Korean newspaper Rodong Sinmun criticized the joint military exercise as an "expression of enmity," adding that no one can guarantee "that the exercise won't lead to hostilities." "If the United States is lost in a fantasy that war on the peninsula is at somebody else's door far away from them across the Pacific, it is far more mistaken than ever," it also said.

Separately, Pyongyang's propaganda website Uriminzokkiri asserted in a commentary that the U.S. and South Korea were staging an exercise to try to wage a nuclear war around the Korean Peninsula, the South Korean news agency Yonhap reported.

"The North Korean army is placing the South Korean military in its crosshairs," the Uriminzokkiri commentary warned. But U.S. Defense Secretary Mattis pointed out that the U.S. had been "very transparent" ahead of the annual military exercises.

Last month North Korea test-launched two ICBMs at highly lofted angles, and outside experts say those missiles can reach some U.S. parts like Alaska, Los Angeles or Chicago if fired at normal, flattened trajectories. Analysts say it would be only a matter of time for the North to achieve its long-stated goal of acquiring a nuclear missile that can strike anywhere in the United States.