SEOUL, South Korea (AP) — North Korea boasted Friday about its recently tested new intercontinental ballistic missile, calling it “the world's most powerful,” a claim viewed as propaganda by outside experts, even though the test showed progress in the North's push to have a more reliable one build arsenal of weapons.

A missile fired by North Korea on Thursday flew higher and stayed in the air longer than any other weapon the country has fired so far. It signaled that the North has made progress toward acquiring a nuclear-armed intercontinental ballistic missile capable of striking the U.S. mainland. But foreign experts assume that the country still has a number of technical issues to overcome before it can acquire such a functioning intercontinental ballistic missile.

On Friday, North Korea's Central News Agency identified the missile as the “Hwasong-19” intercontinental ballistic missile, calling it “the world's most powerful strategic missile” and “the perfected weapon system.”

KCNA said leader Kim Jong Un observed the launch and described it as “an appropriate military action” to express North Korea's determination to respond to moves by its enemies that escalated tensions and threats to North Korea's national security. It said Kim thanked weapons scientists for demonstrating North Korea's “unprecedented strategic nuclear strike capability.”

The South Korean military had previously said North Korea could have tested a solid-fuel rocket, but Friday's KCNA report did not say what fuel the Hwasong-19 ICBM used. Observers say the color of the exhaust flames seen in North Korean media photos of the launch still suggests the new ICBM uses solid fuel.

Before Thursday's test, North Korea's most advanced ICBM was known as the Hwasong-18 missile, which uses solid fuel. Pre-charged solid propellants make rockets easier to move and require much less preparation time for launch than liquid propellants, which must be refueled before launch. This makes it more difficult for opponents to detect solid rocket launches.

North Korea has reported steady progress in its efforts to acquire nuclear missiles in recent years. Many foreign experts believe that North Korea most likely has missiles capable of nuclear attack throughout South Korea, but it does not yet have nuclear missiles capable of reaching the American mainland

There are questions about whether North Korea has the technology to protect warheads from the high-temperature, stressful environment of atmospheric re-entry. Many foreign analysts say North Korea also needs to have improved altitude control and guidance systems for missiles. They say North Korea needs the ability to place multiple warheads on a single missile to defeat its rivals' missile defenses.

All of North Korea's known intercontinental ballistic missile tests, including Thursday's test, have been conducted at a steep angle to avoid neighboring countries. South Korean military spokesman Lee Sung Joon said Thursday that a long-trajectory launch cannot verify a missile's re-entry vehicle technology, although North Korea had previously claimed to have acquired that technology.

Observers say Thursday's launch, North Korea's first intercontinental ballistic missile test in nearly a year, was intended largely to draw American attention days before the U.S. presidential election and to respond to international condemnation over North Korea's alleged sending of troops to Russia in support to respond to his war against Ukraine.

North Korea's reported troop deployment underscores the increasing military cooperation between North Korea and Russia. South Korea, the United States and others fear that North Korea could seek high-tech, sensitive Russian technology to perfect its nuclear and missile programs in exchange for joining the Russia-Ukraine war.