WASHINGTON — After months of quiet, North Korea resumed testing of its ballistic missile program Tuesday, launching its highest missile to date, Defense Secretary Jim Mattis said Tuesday.

“North Korea launched an intercontinental ballistic missile. It went higher, frankly, than any previous shot they’ve taken,” said Mattis, who was at the White House meeting with President Donald Trump. “It’s a research and development effort on their part to continue building ballistic missiles that can threaten everywhere in the world basically.”

The North said in a special televised announcement hours after the launch that it had successfully fired what it called the Hwasong-15, a new nuclear-capable ICBM that's "significantly more" powerful than the North's previously tested long-range weapon. Outside governments and analysts backed up the North's claim to a jump in missile capability.

The missile was launched from Sain Ni, North Korea, and traveled about 1,000 km [or 621 miles] before splashing down in the Sea of Japan, within Japan’s Economic Exclusion Zone, said Pentagon spokesman Army Col. Rob Manning.

Mattis said the South Koreans launched missiles in response, but did not target North Korea.

“In response the South Koreans have fired some pinpoint missiles out into the water to make certain North Korea understands that they could be taken under fire by our ally,” Mattis said. “The bottom line is its a continued effort to build a ballistic missile threat that endangers world peace, regional peace and certainly the United States.”

Initial estimates for the launch put the ICBM’s apogee, or highest point, at 4,500 kilometers, or almost 2,800 miles, with a flight time of about 50 minutes. For comparison, the International Space Station sits about 250 miles above Earth.

Expert analysis of North Korea’s July 24 launch, which had a flight time of 45 minutes with an apogee of 3,700 kilometers, concluded that those numbers would have Los Angeles, Denver and Chicago well within range of the weapon, with Boston and New York City on the outskirts of the range.

If the initial numbers for Tuesday’s launch prove accurate, a wider range of U.S. cities could now be at risk.

David Wright, an analyst with the Union of Concerned Scientists, wrote shortly after the missile test that the qualities of the missile mean North Korea can now hold the United States fully at risk of missile range.

“Such a missile would have more than enough range to reach Washington, D.C., and, in fact, any part of the continental United States,” Wright wrote.

That the launch was taking place was not a surprise, said U.S. Strategic Command spokesman Capt. Brook DeWalt. STRATCOM had observed indicators days before that suggested a launch was imminent, and command leadership watched the launch occur from STRATCOM’s operations center as it took place, DeWalt said.

DeWalt would not provide specifics on where the launch took place, including whether a mobile launcher was used, except to say the missile was not fired from a regular location.

North Korea’s display of ever-increasing capabilities comes as the Trump administration continues to look for ways to dissuade the regime from completing its nuclear weapons program.

“I will only tell you we will take care of it,” Trump told reporters in the same White House media availability where Mattis spoke. “We have Gen. Mattis in the room with us, and we’ve had a long discussion on it. It is a situation that we will handle.”

Wright said that “given the increase in range, it seems likely that it carried a very light mock warhead. If true, that means it would not be capable of carrying a nuclear warhead to this long distance, since such a warhead would be much heavier.”

Mira Rapp-Hooper, a regional expert currently serving as senior fellow at Paul Tsai China Center, says the test changes perception more than reality.

“The biggest substantive difference is that they’ll be able to claim they can hold all of [the continental United States] at risk,” she said. “Which was only a matter of time, but matters a great deal in both countries’ political narratives. Don’t get me wrong — it’s shaping up to be a technically impressive test, but for all intents and purposes, they’ve had us deterred for a nice long while.”

For Rapp-Hooper, the big question now is whether the Trump administration moves beyond the idea that a nuclear-capable ICBM from North Korea can be deterred. Much of the White House policy on North Korea revolves around the idea that such a window exists, and Pyongyang just “just slammed it for emphasis,” she said.

The North American Aerospace Defense Command on Tuesday determined the missile launch did not pose a threat to North America, our territories or our allies, Manning said.

“Our commitment to the defense of our allies, including the Republic of Korea and Japan, in the face of these threats, remains ironclad,” he said. “We remain prepared to defend ourselves and our allies from any attack or provocation.”

The launch was North Korea’s first since mid-September.

The Associated Press contributed to this report.