North Korea’s new long-range ballistic missile will “likely” be able to strike targets on the U.S. West Coast — including San Diego — with a 500-kilogram nuclear warhead in the next one to two years, the U.S.-based monitoring group has said in an analysis.

The influential 38 North website, run by the U.S.-Korea Institute at Johns Hopkins University, said in the report released Monday that the North’s test last week of an intercontinental ballistic missile, the Hwasong-14, highlighted the isolated regime’s technological shortcomings — but also its advances.

While earlier reports said the ICBM could have traveled some 7,000-8,000 km if launched on a standard rather than “lofted” trajectory, aerospace engineer John Schilling said in the analysis, adding that “it can probably do a bit better than that when all the bugs are worked out.”

At present, he said, it “would be lucky to hit even a city-sized target.”

But once the technology is refined, a missile carrying a 500-kg warhead could potentially hit targets up to 9,700 km away, according to Schilling’s projections.

“With a year or two of additional testing and development, it will likely become a missile that can reliably deliver a single nuclear warhead to targets along the U.S. west coast, possibly with enough accuracy to destroy soft military targets like naval bases” such as the one in San Diego, he wrote.

“The North Koreans won’t be able to achieve this performance tomorrow, but they likely will eventually,” he wrote, citing the missile’s re-entry vehicle as the primary challenge facing Pyongyang presently.

In a separate announcement Tuesday, South Korea’s spy agency disputed the North’s claim that it had mastered the re-entry vehicle technology on the Hwasong-14.

“Although North Korea claimed that (the missile’s) heat resistance was verified, whether it re-entered (the atmosphere safely) was not confirmed and the country has no relevant test facility, making it look like it has not secured the technology,” the South’s Yonhap news agency quoted the country’s National Intelligence Service as telling a parliamentary intelligence committee.

The technology is crucial for protecting a warhead from the intense heat encountered when a missile re-enters the atmosphere.

North Korean state media said after the launch that it had verified “all technical features of the payload of the rocket during its atmospheric re-entry, including the heat-resisting features and structural safety of the warhead tip.”

Washington has called the ICBM test “a new escalation of the threat to the United States,” Japan and South Korea, and U.S. Secretary of State Rex Tillerson said last week that “global action … to stop a global threat” was required.

For his part, North Korean leader Kim Jong Un, has said he will continue to dole out “gift packages” of missile and atomic tests in spite of growing international pressure.