A Pentagon spokesman said the personnel would remain for nine months but on departing would leave their equipment behind to be used by follow-on rotations of U.S. forces.
"This addition of forces to Korea is part of the rebalance to the Pacific. It's been long planned and is part of our enduring commitment to security on the Korean peninsula," Army Colonel Steve Warren said.
"This gives the commanders in Korea an additional capacity: two companies of tanks, two companies of Bradleys," he said.
U.S. Secretary of State John Kerry met with South Korean Foreign Minister Yun Byung-se in Washington on Tuesday and stated the U.S. position on nuclear weapons in North Korea.