SEOUL, South Korea (AP) — North Korea boasted Friday that the new ICBM It has just been tested and is “the strongest in the world”, a claim seen as pure propaganda after experts deemed it too large to be useful in a war situation.

The ICBM launched Thursday flew higher and longer than any other weapon North Korea has tested. But foreign experts say the test did not show that North Korea has overcome some of the last remaining technological hurdles to having functioning intercontinental ballistic missiles that could strike the U.S. mainland

North Korea's Central News Agency identified the missile as Hwasong-19 and called it “the world's most powerful strategic missile” and “the perfected weapons system.” Official media said leader Kim Jong Un watched the launch and described it as an expression of North Korea's determination to respond to external threats to North Korea's security.

The color and shape of the exhaust flames seen in North Korean state media photos of the launch indicate that they were rockets pre-charged solid fuel, This makes weapons more agile and harder to detect than liquid fuels, which usually have to be refueled beforehand.

But experts say the photos show that the ICBM and its launch vehicle are both oversized, raising serious doubts about their mobility and wartime survivability.

“What happens when rockets get bigger? The vehicles are also getting bigger. As transport erector launchers get larger, their mobility decreases, said Lee Sangmin, an expert at South Korea's Korea Institute for Defense Analyzes.

The Hwasong-19's length was estimated to be at least 28 meters (92 feet), while modern American and Russian ICBMs are less than 20 meters (66 feet) long, said Chang Young-keun, a missile expert at Seoul's Korea Research Institute for National Strategy . He figured the size of the rocket probably helped South Korean secret services Recognize the launch plan in advance.

“In the event of a conflict, such disclosure would make the weapon the target of a pre-emptive attack by the adversaries, so survivability would be greatly jeopardized,” Chang said.

Lee Illwoo, an expert with the Korea Defense Network in South Korea, said North Korea may have developed a larger missile to carry larger and more destructive warheads or multiple warheads. If that were the case, Lee said North Korea could have used liquid propellants because they produce more thrust than solid propellants. He said some advanced liquid propellants could be stored in rockets for a few weeks before launch.

Lee said North Korea may have placed an empty dummy warhead on the Hwasong-19 to make it fly higher.

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

Among the hurdles it still needs to overcome, experts say, are ensuring its warheads can withstand the heat and stress of atmospheric re-entry, improving guidance systems for the missiles and the ability to deploy multiple warheads on a single missile to combat the Defeating missile defenses.

“Acquiring re-entry technology is currently the most important goal in North Korea's missile development, particularly for ICBMs, but instead ranges continue to be increased. “This may indicate that they still lack confidence in their re-entry technology,” Lee Sangmin said.

Chang said Friday's launch announcement from state media lacked details on the Hawsong-19's technological aspects and focused on advertising.

North Korea's other claims about its weapons capabilities have been met with widespread skepticism from outside.

In June, North Korea claimed to have conducted tests a multi-warhead missile in the first known launch of such a weapon, but South Korea said the weapon exploded instead. In July, North Korea said it had tested a new tactical ballistic missile capable of doing this “a super-large warhead” South Korea said the claim was an attempt to cover up a botched launch.

North Korea's missile program continues to pose a major regional security risk, with the country openly threatening to use its nuclear missiles against its rivals. In a joint statement on Thursday, the foreign ministers of South Korea, the United States and Japan condemned the launch of an intercontinental ballistic missile as a violation of U.N. Security Council resolutions and said they were determined to step up efforts to use North Korea's illicit sources of revenue to finance its missiles and missiles to block nuclear programs.

South Korea's Foreign Ministry said on Friday it had imposed unilateral sanctions on 11 North Korean individuals and four entities over their alleged roles in procuring missile components and generating foreign currency to finance Pyongyang's weapons program. The sanctions are largely symbolic, as financial transactions between the Koreas have been suspended for years.

Also on Friday, South Korea and the United States conducted their first joint fire exercise using unmanned aerial vehicles to demonstrate their readiness. According to the South Korean Air Force, the South Korean reconnaissance aircraft RQ-4B “Global Hawk” and the US combat drone MQ-9 Reaper were mobilized for the training. South Korea and the United States have expanded their regular military exercises to address North Korea's evolving nuclear threat.

Observers say Thursday's launch, the North's first intercontinental ballistic missile test in nearly a year, was intended largely to attract American attention and respond to international condemnation just days before the U.S. presidential election North Korea's reported troop deployment to Russia to support its 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 return for joining the Russian-Ukrainian war.