As North Korea continues to develop its weapons programs and strengthens its military ties with Russia, a reduction of U.S. troops based in South Korea would be "problematic," the commander of U.S. Forces Korea said.

South Korea’s military fired warning shots after North Korean soldiers crossed the rivals’ tense border, South Korean officials said. South Korea’s military said in a statement that about 10 North Korean soldiers returned to the North after South Korea made warning broadcasts and fired warning shots.

South Korea's military fired warning shots after North Korean soldiers crossed the rivals' tense border on Tuesday, South Korean officials said, the first known border intrusion by North Korea in nearly a year.