Updated: 11:30 p.m. Eastern

Updated: 9:30 p.m. Eastern

North Korea has reportedly launched an Unha-3 rocket from its Sohae-ri launch facility and ostensibly carrying a satellite on board, with early signs indicating the launch could have been a success. Then, on late Tuesday, the North American Aerospace Defense Command – which oversees the U.S. and Canada's air defense – released a statement noting that North Korea appears to have successfully launched an 'object' into orbit.

"North American Aerospace Defense Command officials acknowledged today that U.S. missile warning systems detected and tracked the launch of a North Korean missile at 7:49 p.m. EST," noted the statement. "The missile was tracked on a southerly azimuth. Initial indications are that the first stage fell into the Yellow Sea. The second stage was assessed to fall into the Philippine Sea. Initial indications are that the missile deployed an object that appeared to achieve orbit. At no time was the missile or the resultant debris a threat to North America."

Note these are still initial indications. Early South Korean and Japanese media reports indicated that the rocket appears to have roughly tracked with coordinates Pyongyang provided earlier to the International Maritime Organization, in a standard move to warn ships and aircraft to stay out of areas where rocket debris would be expected to fall. Now with a potentially successful satellite launch, it'd be a major success for North Korea, especially when compared to the last time North Korea fired a rocket. That launch, in April, failed after the rocket blew up after only 90 seconds, and never entered its second stage.

What was partly unexpected is the launch time, but only partly. The North Koreans originally gave a launch window between Dec. 10 and 22. On Monday, that launch window was extended to Dec. 29 and the rocket was reportedly pulled off its launch pad, according to the Yonhap News Agency. North Korea's state-run news agency KCNA also cited troubles on Monday with the rocket's first-stage engine as the reason for the extended window. That led to speculation that Pyongyang was grappling with unresolved technical problems leftover from a failed launch seven months ago. Perhaps not.

That report indicated Pyongyang's Unha-3 multiple-stage rocket – which was being readied for launch as recently as last week – had disappeared. A South Korean official told the agency that Pyongyang moved the rocket back to its assembly line in order to fix unspecified "technical problems." Previously, Pyongyang admitted on Monday there was something wrong with the rocket's engine. According to North Korea's state-run news agency KCNA, "scientists and technicians ... are pushing forward the preparations for a launch" but they "found technical deficiency in the first-stage fire control engine module of the rocket."

South Korean media had previously reported that the rocket had been assembled and ready for fueling before it was taken down. But satellite images released late last week and dissected by North Korea observer Nick Hansen showed only a partially completed first-stage rocket, fueling speculation the Pyongyang was bogged down by snowfall. But then, that can happen when you try and launch a rocket in North Korea in the winter.

None of those were initially good signs for Pyongyang, which is attempting its fifth try at launching a satellite into orbit – the four previous attempts have all ended in failure. Or Pyongyang at least claims it's a satellite program: The United States believes it's actually a cover for a military weapons program, and moved four Navy guided-missile destroyers into position in case the rocket threatens Japan or the Philippines. (There's now no indication the U.S. or Japan tried to shoot the rocket down.) And days before, North Korea was assuring the world that it had fixed the technical problems that caused a much-hyped rocket launch in April to fail after 90 seconds and crash into the Yellow Sea.

It's impossible to know exactly what caused that previous rocket to fail, but one running theory has it being a problem with either the guidance system or first-stage engine. Earlier this month, Japanese news agency *Kyodo News (alas, behind a paywall) *reported that U.S. and Japanese officials had completed analyzing telemetry data from the April launch, which indicated one of those two culprits, or even a structural failure.

"The Kyodo report is interesting in part because if U.S. and Japanese experts were poring over the data until October or November to understand the failure, it calls into question whether North Korean engineers could have identified and remedied the problems in time for a December launch," wrote David Wright, a missile expert with the Global Security Program at the Union of Concerned Scientists.

That also tracked with what Victoria Samson, a rocket expert with the Secure World Foundation, told Danger Room last week: The time frame between launches may just be too short for North Korea to have made significant upgrades. But Adm. Samuel Locklear, the U.S. Pacific Command chief, sounded a little freaked out over the possibility that North Korea has "progressively gained better technology over time."

Still, rocketry is an extraordinarily difficult engineering task. It's not uncommon for developed countries with advanced rocket programs to fail at it. Fixing one problem could create unintended faults to pop up elsewhere. Worse, North Korea uses old Soviet rocket parts and cobbles them together, and lacks the technical expertise and manufacturing processes needed for rockets to work well. Even if a rocket successfully launches a satellite it into space, it doesn't mean it can hit the United States, or carry much of a payload – let alone a nuclear one.