Censor.NET informs citing Associated Press.
David Shear, the assistant secretary for Asia issues, says the exercise was temporarily halted so that the U.S. and South Korea could talk and coordinate over the recent exchange of artillery fire across the border.
He says U.S. forces are at an increased security status for the exercise and that the U.S. is continuing to monitor the situation closely.
Earlier, U.N. Secretary-General Ban Ki-moon has expressed deep concern over rising tensions between North and South Korea and urged them to engage in dialogue to promote peace.
U.N. spokeswoman Eri Kaneko said Ban also urged the two Koreas to refrain from taking any further measures that might increase tensions.
Ban is a former South Korean foreign minister.
Tensions have escalated since South Korea accused rival North Korea of shelling a border town on Thursday and retaliated with dozens of artillery rounds. North Korea has threatened further action unless Seoul ends loudspeaker broadcasts of anti-North Korean propaganda at the border.
North Korea's ambassador to Russia has accused South Korea of lying about alleged North Korean artillery strikes and asked for the world's help in defusing rapidly growing tensions between the two countries.
At a news conference in Moscow on Friday, Ambassador Kim Hyun Joon attributed the tensions to what he called military and political provocations by the United States and South Korea.
He repeated North Korea's threat of military action if South Korea does not meet a Saturday deadline for removing loudspeakers along their border that recently resumed broadcasting anti-North Korean propaganda after a lull of 11 years.
South Korea has vowed to continue the broadcasts, which were restarted after it accused North Korea of planting land mines in the DMZ along their border that maimed two South Korean soldiers.
South Korea fired dozens of artillery shells across the border on Thursday after accusing North Korea of artillery strikes.