North Korea's satellite launch failure on Wednesday was likely to have happened because of an unexpected technical error, rather than leader Kim Jong-un’s impatience to improve surveillance capabilities, according to defector-turned-Assemblyman Rep. Tae Yong-ho.

Tae, who was a senior diplomat for North Korea before defecting to Seoul in 2016, said in a press release that the spy satellite’s attempted launch was a key military milestone that has been a long time in the making. For the past two years at least, North Korea has been working on new engines and fuels to succeed in launching what would be its first satellite of its kind.

North Korean state media KCNA said in a rare admission its first spy satellite failed to reach space, and that the rocket carrying the satellite crashed into sea. It blamed an “unstable” fuel, and that there had been a “serious defect.” This admission belied the failure was caused by an error that was previously unseen, Tae said.

Events in the run-up to the launch also indicated Kim was confident the launch would succeed, Tae said. Kim appearing at the nonpermanent satellite launch preparatory committee on April 19, accompanied by his young daughter Ju-ae, was an announcement to the world that North Korea completed developing its first military spy satellite.

When Kim sought the nonpermanent satellite launch preparatory committee about a month later on May 17, he was making final checks. There, the vice minister for foreign affairs, Kim Sun Kyung, was seen beside the North Korean leader. Tae said it was unprecedented for a foreign affairs official to attend a satellite launch preparatory meeting, and that this showed Kim was mindful of international norms regarding space launches.

Tae noted that the failed attempt on Wednesday comes just a day after Ri Pyong-chol, a top North Korean military official, vowed that the country would be sending a first spy satellite into orbit.

Tae added that it still remained to be seen if North Korean authorities will officially admit to and announce the failure to its people on TV this evening or on Thursday in the state-run newspaper Rodong Sinmun. If they do, it would mean that they are still confident the next launch will be successful.

South Korea’s spy agency believes it would take North Korea “several weeks” to fix the error that is believed to have caused the launch to fail, Rep. Yoo Sang-bum on the Assembly intelligence committee told reporters on Wednesday.

The launch led to emergency warnings being placed across Seoul in the morning, including a falsely issued evacuation alert, which were later lifted.