A South Korean army soldier watches the North Korea side from the Unification Observation Post in Paju, South Korea, near the border with North Korea, Wednesday, Dec. 25, 2019. AP

A U.S. Army base in South Korea accidentally sounded an emergency siren Thursday night, sending some soldiers into a frenzy amid threats of an unwanted "Christmas gift" from North Korea, news reports said.

The incident occurred at Camp Casey in Dongducheon, 40 kilometers north of Seoul, the closest U.S. Army base to the North Korean border.

The Washington Post reported that the siren went off around 10 p.m. instead of taps, the bugle call played at military funerals and on military bases to mark the end of the day.

Army Lt. Col. Martyn Crighton, a spokesman for the 2nd Infantry Division, called it "human error."

"The operator immediately identified the mistake and alerted units on Camp Casey of the false alarm," CNN quoted Crighton as saying in a statement.

He told The Post that the siren heard would normally warn soldiers to begin "alert procedures."

A sense of alarm gripped the base, according to posts on social media.

"So someone on Casey decided to hit the go to war button instead of taps, it was a false alarm but goddam did the entire battery got riled up," CNN quoted one commenter as saying on the U.S. Army Reddit thread.

"I've been here for like 2 weeks and I hear some alarm going off. Call some people in my unit and they say they never heard it before. My damn blood pressure man," wrote another.

The false alarm "had guys running up and down the halls in full uniform," said another post.

Tensions have run high amid concerns North Korea could launch an intercontinental ballistic missile as its threatened "Christmas gift" for the U.S.

Christmas passed with no "gift," but South Korean and U.S. officials have remained on high alert for a possible launch or any other provocation from Pyongyang amid no sign of a breakthrough in the stalled denuclearization talks between North Korea and the U.S.

Pyongyang has threatened to take a "new way" unless Washington takes steps to salvage the negotiations before the end of the year, suggesting it will revert to nuclear and long-range missile tests short of U.S. sanctions relief and other concessions in exchange for its denuclearization.

Reflecting the nerves, Japanese public broadcaster NHK also sent a news bulletin Friday that incorrectly reported a North Korean missile launch into waters east of Japan. (Yonhap)