SEOUL, South Korea — North Korea has launched several unidentified short-range missiles, a South Korean military official confirmed to NBC News.

They were launched over the course of about 30 minutes just after 9 a.m. Saturday local time off the eastern area on the Hodo Bando peninsula. South Korean and U.S. authorities are analyzing the details concerning the missile launch, according to the military official.

The official initially had said one missile was launched.

A South Korean military official said the projectiles traveled between 43 and 124 miles, adding that the military has increased surveillance to watch for any more launches.

"We confirm that what North Korea launched today was not ballistic missiles," a South Korean military official told NBC News.

The White House was monitoring the situation, press secretary Sarah Sanders said Friday night. "We are aware of North Korea’s actions tonight," she said. "We will continue to monitor as necessary.”

President Donald Trump had been "fully briefed" on the launch by national security adviser John Bolton, a senior administration official told NBC News on Friday night.

Anything in this very interesting world is possible, but I believe that Kim Jong Un fully realizes the great economic potential of North Korea, & will do nothing to interfere or end it. He also knows that I am with him & does not want to break his promise to me. Deal will happen! — Donald J. Trump (@realDonaldTrump) May 4, 2019

South Korea's foreign minister also discussed the missile launch on the phone with U.S. Secretary of State Mike Pompeo Saturday.

"Both parties agreed to continuously conduct additional analysis on today's launch and keep communications flowing," a South Korean foreign ministry official told NBC News.

In the wake of the launch, Japanese officials said North Korean missiles have not reached anywhere near the country's coast and that Japan is not facing any security threat.

The weekend launch is likely a sign of Pyongyang's growing frustration at stalled diplomatic talks with Washington over its nuclear arsenal.

Earlier this year, Trump and North Korean dictator Kim Jong Un abruptly ended a summit and were unable to negotiate a denuclearization deal.

The president indicated then that the discussions stalled over Kim's demand that all sanctions be lifted in exchange for concessions on Pyongyang's nuclear weapons program. The U.S. has indicated that the sanctions will stay in place until North Korea makes more significant moves.

There have since been no publicly known high-level contacts between the U.S. and North Korea, although both sides say they are still open to a third summit.

Researchers at Beyond Parallel, a project sponsored by the defense think tank Center for Strategic and International Studies, found in March that North Korea was pursuing the "rapid rebuilding" of the long-range rocket site at Sohae Launch Facility.

Beyond Parallel reported that the activity at Sohae, photographed on March 2, is "evident at the vertical engine test stand and the launch pad's rail-mounted rocket transfer structure."

"The activity they are undertaking now is consistent with preparations for a test, though the imagery thus far does not show a missile being moved to the launch pad," Victor Cha, one of the authors of the report, said.

Stella Kim reported from South Korea, with Doha Madani from New York and Yuliya Talmazan in London.