SEOUL, South Korea — It was the night after North Korea's "Christmas gift" failed to materialize, but all through one U.S. military base a siren was blaring.

Camp Casey, which sits near the border between North and South Korea, had a scare earlier this week when an alert siren was sounded by accident just as the world was on edge amid concern about a potential provocation from Pyongyang.

The siren went off instead of a bugle call on Thursday evening because of "human error," Lt. Col. Martyn Crighton, a public affairs officer for the 2nd Infantry Division, told NBC News on Saturday.

"The operator immediately identified the mistake and alerted units on Camp Casey of the false alarm," he said in a statement.

Officials in the region have been on high alert after North Korea set a year-end deadline for the United States to make new concessions amid deadlocked talks over the country's nuclear arsenal.

A recent analysis of satellite images suggests North Korea has expanded a factory linked to the production of long-range nuclear missiles. Amid these concerns, South Korean media reported that the U.S. flew several spy planes over the Korean Peninsula during the holiday.

The U.S. military established a presence in South Korea following World War II in an effort to disarm Japan and later fought alongside the country in the 1950-53 Korean War. The country now pays the U.S. about $924 million per year to maintain 28,500 American troops on its soil to deter aggression from North Korea.

South Korea signed a deal earlier this year to pay more for U.S. troop presence after a demand from Trump and rounds of failed negotiations caused worries about their decades-long alliance. JUNG YEON-JE / AFP/Getty Images

A day before the siren at Camp Casey, the Japanese broadcaster NHK also caused panic by mistakenly sending a news alert saying North Korea fired a missile that landed off the country's northeastern island of Hokkaido. The broadcaster explained the alert was for media training purposes in its apology.

Despite President Donald Trump's attempts at diplomacy with North Korean leader Kim Jong Un, which he has made a centerpiece of his foreign policy efforts, relations have been rocky.

After an exchange of saber-rattling in 2017, Trump became the first U.S. president to meet with his counterpart at a summit in Singapore in 2018. Trump said at the time that the pair had "developed a very special bond," and described Kim as "a very talented man."

But in February, talks between the two leaders in Hanoi abruptly broke down. That was, however,followed by another historic meeting in June, when Trump took an unprecedented step into North Korea.

An October meeting between their negotiators in Sweden then also broke down.

More recently, Kim has said that North Korea could seek a “new path” if the U.S. persists with sanctions and pressure against the North. It has also threatened to lift a self-imposed moratorium on nuclear and long-range missile tests and resume launches over Japan.

Trump played down North Korea’s warnings, saying Tuesday that he could receive a “nice present instead.”

“Maybe it's a present where he sends me a beautiful vase as opposed to a missile test. Right? I may get a vase, I may get a nice present from him, you don’t know. You never know,” the president jokingly told reporters after a Christmas Eve video conference with U.S. troops.

“Let's see what happens. Everybody’s got surprises for me but let's see what happens. I handle them as they come along,” he added.

Stella Kim reported from Seoul, and Linda Givetash from London.