North Korea's successful launch in July of a new type of intercontinental ballistic missile was likely the result of technical cooperation sourced to Russia, a U.S. national security policy expert said in a report on Thursday.

Theodore Postol, professor emeritus at the Massachusetts Institute of Technology, analyzed the reported physical dimensions and flight trajectory data of North Korea's Hwasong-18 and found them to be "nearly identical" to that of the Russian ICBM Topol-M.

In the most recent ICBM test on July 12, Pyongyang showed progress through the "sudden appearance" of a solid-fueled ICBM, which came in contrast to liquid propellant ICBMs the secretive country has demonstrated over the past few years, according to the report posted on the website of the Center for Strategic and International Studies.

File photo shows a Hwasong-18 intercontinental ballistic missile on display during a military parade in Pyongyang in July 2023. (KCNA/Kyodo)

The solid-fueled ICBM launch occurred only months after an engine test, and "the sudden appearance of these advanced capabilities is difficult to explain without cooperation from the Russian government and its scientists," the report said.

A solid-fuel missile does not require fueling prior to launch like a liquid-fuel missile, making it harder for adversaries to detect launch preparations.

Touching on growing Russia-North Korea ties, including the transfer of munitions in support of the Russian invasion of Ukraine, Postol also said the potential transfer of the Topol-M missile or its technology would take cooperation between Moscow and Pyongyang against the United States and its Indo-Pacific allies to "a new and more dangerous level."

The Hwasong-18 was fired toward the Sea of Japan on a steep lofted trajectory, marking a record 74-minute flight time for a projectile launched by North Korea, according to the Japanese government.

Postol said the missile has the ability to penetrate existing U.S. ballistic missile defenses and deliver multiple nuclear weapons to targets in the continental United States.

"A Hwasong-18 missile force will require the U.S. to consider additional concepts for missile defense including the use of airborne drone interceptors," he said.

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