SEOUL--South Korea said North Korea fired a ballistic missile toward the sea, but the launch likely failed Wednesday night.

The launch came hours after Seoul said it would resume front-line aerial surveillance in response to the North’s spy satellite launch on Tuesday night.

South Korea’s Joint Chiefs of Staff said in a brief statement early Thursday a missile was launched from the Pyongyang region toward the North’s eastern waters but that the launch was believed to have ended in failure. It gave no further details such as what type of missile was fired and what happened to it.

The launch was North Korea's first known weapons firing in more than two months.

It followed South Korea's announcement earlier Wednesday that it decided to partially suspend an inter-Korean agreement and resume flying surveillance aircraft along the border in reaction to the North's satellite launch.

North Korea on Thursday lambasted the South Korean move, saying it'll deploy more powerful and new weapons at the border in a tit-for-tat measure.

South Korea, the U.S. and Japan have strongly condemned the North’s satellite launch on Tuesday night because they believe it was meant to improve the country’s missile technology as well as establish a space-based surveillance system.

U.N. Security Council resolutions prohibit any satellite liftoffs by North Korea, viewing them as covers for testing its long-range missile technology. The North says it has a sovereign right to launch satellites.

The North's neighbors are trying to confirm whether its satellite launch was successful as it claimed and whether the satellite can perform reconnaissance functions.

South Korea’s military said it assessed that the satellite had entered orbit. But it said it needs more time to verify whether it works. Earlier, the Pentagon said it was assessing the success of the launch, while Japan said there had been no confirmation of the North’s report on the satellite entering orbit.

North Korea’s space agency said its Malligyong-1 satellite was placed in orbit on Tuesday night, about 12 minutes after liftoff.

Leader Kim Jong Un watched the satellite launch on site. He later visited the Pyongyang control center of the North’s space agency, where he was briefed that the satellite would officially begin its reconnaissance mission from Dec. 1, following a period of fine-tuning, according to state media.

The North’s official Korean Central News Agency reported that Kim was presented with satellite photos of Anderson Air Force Base, Apra Harbor and other U.S. military facilities in the U.S. Pacific territory of Guam, which it said were taken Wednesday morning.

It didn’t publicize the photos, and many experts remain skeptical about whether the North Korean satellite is advanced enough to conduct meaningful military reconnaissance.

In December, when North Korea released black-and-white satellite photos of South Korean cities following a test launch, many experts said the imagery was too crude for surveillance purposes. In 2012 and 2016, North Korea placed Earth observation satellites into orbit, but experts say neither has ever transmitted imagery back to North Korea.

North Korea used the same satellite in its two failed launches in May and August. South Korea’s military retrieved debris from the first launch and assessed at the time the satellite wasn’t sophisticated enough to perform military reconnaissance.

Before Tuesday’s launch, South Korean officials said North Korea was likely receiving Russian technological support for its spy satellite launch program as part of the two countries’ push to boost their partnerships.

The U.S., South Korea and others accuse North Korea of shipping conventional arms to support Russia’s war in Ukraine in exchange for receiving high-tech Russian technologies to enhance its own military programs. Both North Korea and Russia have denied the accusations.

A spy satellite is among an array of sophisticated weapons systems that Kim wants to acquire. Experts say he would eventually aim to use his enlarged arsenal to win sanctions relief and other concessions from the U.S. when diplomacy resumes.

Some civilian experts said North Korea’s Malligyong-1 satellite is likely capable of only detecting big targets like warships or planes. But by operating several such satellites, North Korea could still observe South Korea at all times, they said.

Animosities run high on the Korean Peninsula due to North Korea's series of weapons tests since last year and the expansion of U.S.-South Korean military drills.

When Heo Tae-keun, South Korea’s deputy minister of national defense policy, announced the partial suspension of the 2018 inter-Korean agreement, he said South Korea will “promptly and strongly punish” North Korea if it uses the South Korean step as a pretext to launch another provocation. Heo called the North's satellite launch “a grave provocation that threatens our national security.”

North Korea's Defense Ministry responded Thursday it will get South Korea to face “searing consequences” over its decision. It said North Korea won't be bound by the 2018 deal any longer and restore all the steps it has taken to ease frontline military tensions under the agreement.

The North's space agency said the satellite would help improve the North’s war readiness in the face of “the enemies’ dangerous military moves.” The agency said North Korea will soon launch several more spy satellites to better monitor South Korea and other areas.

The 2018 agreement, struck during a short-lived era of reconciliation between the rival Koreas, created buffer and no-fly zones along the countries’ heavily fortified border. Under the deal, the Koreas were required to halt front-line aerial reconnaissance and live-fire exercises. They also removed some of their guard posts and land mines at border areas.

The deal invited conservative criticism in South Korea, with critics saying it significantly restricted the operation of the country’s aerial surveillance assets, which are much more superior to North Korea’s. They also accused the deal of heavily benefiting North Korea, because it only called for mutual reductions of conventional military strength while leaving the North’s growing nuclear arsenal intact.