SEOUL — South Korea and the United States began annual military drills Monday that North Korea calls a precursor to war. US officials said the two-week Ulchi Freedom Guardian drills involves more than 80,000 troops from the United States, South Korea, and seven countries that fought with them in the 1950-53 Korean War.

Pyongyang has repeatedly threatened to attack Seoul over perceived insults and denounces the exercises as preparation for a preemptive attack. Seoul is still angry over a North Korean rocket launch in April that the United Nations called a front for a banned long-range missile test. North Korea says it was a satellite launch.

Pyongyang’s official media said leader Kim Jong Un recently visited military units involved in a deadly 2010 artillery exchange with South Korea. In Washington, State Department spokeswoman Victoria Nuland said the exercises are routine and urged North Korea to refrain from ‘‘bellicose statements.’’

North Korea routinely vows retaliation against the drills, calling them provocative.

In his tour of military units on western border islands, Kim told the military to prepare for ‘‘sacred war’’ if even a single shell hits the country’s territory, the official Korean Central News Agency said Saturday. The islands Kim toured included the one closest to South Korea’s Yeonpyeong Island, which North Korea shelled in November 2010.

North Korea’s Foreign Ministry called the drills ‘‘a military expression of the US hostile policy’’ that justifies the regime’s decision to bolster its nuclear war deterrent, the news agency said Monday.