TOKYO — North Korea has taken another bold step toward achieving its stated goal of being able to send a nuclear weapon to the U.S. mainland, firing an intercontinental ballistic missile late Friday that highlights the regime’s rapid technological progress.

The missile flew almost straight up for 45 minutes and reached a height of about 2,300 miles before crashing into the sea off Japan. But if it had been launched on a normal trajectory, the missile could theoretically have reached Chicago and perhaps even New York, experts said.

This latest provocation compounds the problem facing the Trump administration and North Korea’s neighbors: How to stop the regime of North Korean leader Kim Jong Un from making progress with its nuclear weapons program.

“Kim Jong Un does seem hellbent on acquiring the capability to reach the United States with nuclear weapons,” said Sharon Squassoni, director of the Proliferation Prevention Program at the Washington-based Center for Strategic and International Studies (CSIS).

The Pentagon and South Korea’s joint chiefs of staff both said they had detected the launch, which occurred Friday at about 11:11 p.m. North Korea time. The late-night launch was unusual, as North Korea usually fires missiles shortly after dawn.

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“We assess that this missile was an intercontinental ballistic missile, as had been expected,” said Navy Capt. Jeff Davis, a Pentagon spokesman.

The North American Aerospace Defense Command “determined the missile launch from North Korea did not pose a threat to North America,” Davis said.

American officials assessed that the missile flew on a “lofted” trajectory to reach an apogee of 2,300 miles, before landing about 620 miles from its launch site in Chagang province in northwestern North Korea, near the border with China.

This is something that North Korea has been doing to test its missiles without firing them over Japan, an even more incendiary move.

The missile landed within Japan’s exclusive economic zone in the Sea of Japan, chief cabinet secretary Yoshihide Suga told a news conference convened early Saturday morning. Analysts said it landed off the coast of the northern island of Hokkaido.

“We cannot tolerate North Korea’s repeated provocations like this,” Suga said. “We have made a strong protest to North Korea and condemned this act in the strongest terms.”

In this July 4, 2017, file photo distributed by the North Korean government, North Korean leader Kim Jong Un, second from right, inspects the preparation of the launch of a Hwasong-14 intercontinental ballistic missile in North Korea’s northwest. (AP/AP)

If the missile had been fired on a trajectory designed to maximize its range, it could have flown 6,500 miles, said David Wright, co-director of the Global Security Program at the Union of Concerned Scientists. This is without taking into account the rotation of the Earth, which  increases the range of missiles fired to the east.

“Los Angeles, Denver, Chicago appear to be well within range of this missile, and that Boston and New York may be just within range,” Wright said. Washington may still be just out of range, he added.

These are only estimates, and experts do not know what kind of payload the missile was carrying, a factor that influences range.

But with its rapid succession of tests, North Korea is showing steady and observable technical progress that has alarmed analysts and officials alike.