TOKYO — Twice a year, American and South Korean troops get together for large-scale war games to prepare for a possible attack by North Korea. And year after year, the North condemns the joint exercises as a rehearsal for an invasion and demands that they be called off.

Now, with President Trump and North Korea’s leader, Kim Jong-un, recently trading threats of nuclear war, another round of the biannual drills is set to begin on Monday in South Korea. They are the first to be conducted since North Korea test-fired missiles that appear capable of hitting the United States, and some are asking whether they might be used as a bargaining chip to persuade the North to freeze its nuclear program.

The United States and South Korea describe the exercises as defensive in nature. North Korea, on the other hand, views them as much more threatening, particularly components that include plans for assassinations of the country’s leadership in the event of an outbreak of war. Last weekend, the North said the exercises were “kicking up war zeal.”

Two years ago, the North proposed a temporary moratorium on nuclear tests if Washington canceled the joint biannual military exercises. The exercises starting on Monday are known as Ulchi-Freedom Guardian and consist mainly of computer simulations carried out in a large bunker in mountains south of Seoul. Much larger war games in the spring usually involve live-fire training and tank movements as well as drills with ships and aircraft. China has also recently suggested a similar two-sided freeze, although the United States has so far refused.