North Korea threatened to halt talks with Seoul unless it pulls out of joint U.S.-South Korean military drills. The talks are aimed at reducing tensions between the two armies that face each other across the heavily fortified border, known as the Demilitarized Zone.
The United States has about 30,000 troops in South Korea working with about 690,000 South Korean troops.
North Korea has most of its million-strong military positioned near the Demilitarized Zone.
The two Koreas are technically still at war because the 1950-1953 Korean War ended with a truce and not a peace treaty.
South Korea is also part of separate six-country talks aimed at ending North Korea's nuclear weapons programs. Those talks have hit a snag over a U.S. crackdown on firms it suspects of helping North Korea in illicit activities such as counterfeiting.