North Korea flight tested a new intermediate-range missile the Pentagon assesses was practice for the reentry of a nuclear warhead into the atmosphere, according to defense officials.

The missile launch was tracked from Kosong in southeastern North Korea and was identified by U.S. intelligence agencies as a KN-17, a missile capable of carrying a nuclear warhead up to 3,400 miles—enough to reach Alaska and Guam. The Pacific island of Guam is a key hub for the U.S. military in the Pacific.

The missile launched around 4:30 p.m. Eastern time on Saturday and attained the unusually high altitude of around 1,200 miles to test its capability of delivering a nuclear warhead through the through the earth's atmosphere during reentry.

"This is a key step [in nuclear missile development] and something they currently cannot do," said a defense official familiar with intelligence reports.

After reentering the atmosphere, the missile impacted in the Sea of Japan around 400 miles from its launch point.

The KN-17 was shown during a military parade in Pyongyang last month on a tracked mobile launcher.

The test Saturday was conducted from a static launch stand, not a mobile launcher, the defense official said.

The latest missile test drew a harsh reaction from the White House.

"North Korea has been a flagrant menace for far too long," the White House said in a statement. "Let this latest provocation serve as a call for all nations to implement far stronger sanctions against North Korea."

Nikki Haley, U.S. ambassador to the United Nations, said Sunday the latest missile test has undermined the prospect of direct talks between North Korea and the United States.

President Trump has said he would be willing to meet North Korea's Kim Jong Un, while Pyongyang hinted prior to Saturday's test it might be willing to hold talks.

Asked on ABC's This Week what circumstances would produce talks, Haley said: "It's not this. Having a missile test is not the way to sit down with the president, because he's absolutely not going to do it."

Haley said the United States is "working better with China than we ever have" on North Korea, and that Russia also is concerned about Pyongyang's nuclear missile programs.

"And so what we're going to do is continue to tighten the screws," she said. Among the options being studied are additional sanctions targeting North Korea's oil imports, other energy imports, and shipping and exports.

White House Press Secretary Sean Spicer said the latest test bolsters the case for stronger sanctions on North Korea.

"There is no question that North Korea continues to threaten the United States, our allies Japan, South Korea, and its neighbors, including both China and Russia," Spicer told reporters Monday.

"We are calling on all those folks in the region, particularly China and Russia, to do everything they can in terms of sanctions and to help resolve the situation and bring stability to the peninsula."

The Trump administration has backed off tougher policies toward China following the recent summit between President Trump and Chinese President Xi Jinping after promises that Beijing would do more to curb North Korea's provocations.

North Korea was expected to conduct a sixth underground nuclear test last month but so far has held off. The delay has fueled speculation that China pressured North Korea not to conduct the test.

North Korea's state-run KCNA news agency said Monday the missile it calls a medium-range Hwasong-12 is another "juche weapon," or self-reliance weapon. The dispatch said Kim was present for the test and "hugged officials in the field of rocket research, saying that they worked hard to achieve a great thing."

"The test-fire was conducted at the highest angle in consideration of the security of neighboring countries," KCNA said, adding the launch "aimed at verifying the tactical and technological specifications of the newly developed ballistic rocket capable of carrying a large-size heavy nuclear warhead."

"It also verified the homing feature of the warhead under the worst re-entry situation and accurate performance of detonation system," the agency said.

The test followed the election last week of a new South Korean president, Moon Jae In, who announced he will modify Seoul's policies toward North Korea in a bid to improve relations.

Moon said during his election campaign he would seek a dual-track policy of denuclearization and dialogue with the rogue state.

"Tests are a way for the [North Korean] regime to set the parameters of its relations with its neighbors. This launch could be designed to see how Moon reacts," Ken Gause, a senior analyst at U.S.-based CNA Corp., told South Korea's semi-official Yonhap News Agency.

The Pentagon's Defense Science Board said in a report made public in January that ballistic missile advances threaten the survivability of U.S. foreign military bases and overseas assets.

"The study found that the survivability of those assets could be very problematic given recent increases in adversary ballistic and cruise missile inventories and capabilities, in combination with a continued U.S. trend to make its regional offensive capabilities increasingly dependent on fewer and fewer forward based assets," said Craig Fields, the board chairman.

The board recommended spending $2.5 billion annually on passive and active defenses, as well as offensive weapons less vulnerable to missile attacks.

The new IRBM is believed by non-government experts to have been tested for the first time April 5 when it failed shortly after launch.

A second suspected KN-17 test may have taken place April 16 and blew up several seconds after launch. A third launch, also a failure, took place April 29.

The three earlier failures prompted news reports indicating the United States reportedly sabotaged the launches by arranging for faulty missile components for the North Korean missile program.

Photos of the new missile show fins near the nose cone, indicating the weapon may be capable of maneuvering to defeat missile defenses.

The KN-17 is assessed by the National Air and Space Intelligence Center to be a single-stage, liquid fueled road mobile missile.

The KN-17 is a strategic nuclear missile that has been shown in military parades, according to an early assessment by the center.

Intermediate-range missiles are used to "hold at-risk or strike logistics nodes, regional military bases including airfields and ports, and naval assets," the center said.

"North Korea has an ambitious ballistic missile development program and has exported missiles and missile technology to other countries, including Iran and Pakistan," the center's 2013 report said. "North Korea has also admitted its possession of nuclear weapons. It has displayed new IRBMs and older No Dong MRBMs in recent military parades."