SEOUL (Kyodo) -- South Korea and the United States on Monday began a large-scale annual joint military exercise to strengthen their combined defense capabilities and counter the threat from North Korea, the first such drill since U.S. President Donald Trump took office in January.

The Freedom Shield exercise, slated to run for 11 days through March 20, will reflect evolving challenges posed by North Korea's military development as well as its growing partnership with Russia amid its troops' participation in the war in Ukraine, the South Korean and U.S. militaries said last week.

North Korea condemned the start of the military exercise as a provocative act leading to an "acute situation" on the Korean Peninsula that may "spark off a physical conflict," its state media said Monday. It said it will redouble efforts to keep the peace by strengthening defense, including through its nuclear force.

South Korea's Joint Chiefs of Staff and U.S. Forces Korea said in a briefing last Thursday that some 19,000 troops will be deployed for the exercise, with plans to hold 16 brigade-level field training sessions, compared with 10 last year.

The U.S. military in South Korea reaffirmed Washington's security commitment to Seoul under the new Trump administration, vowing to put its utmost effort into securing the country and its people from any possible enemies.

"The ironclad commitment to the ROK is as strong as ever," said Col. Ryan Donald, spokesman for the U.S. forces in South Korea, using the acronym of the country's official name, the Republic of Korea. "What we are doing right now is building our readiness capabilities to defend the ROK against any threat."

The two allies will train in the domains of land, sea, air, cyber and space to strengthen interoperability while showcasing their combined deterrence capabilities, the militaries said.

In addition to South Korea and the United States, a member country of the United Nations Command overseeing the armistice that ended the 1950-1953 Korean War, several other members of the command will take part in the annual military exercise, according to the South Korean military.