By Tom Balmforth and David Gauthier-Villars
KYIV (Reuters) - Ukrainian state prosecutors say they have examined debris from 21 of around 50 North Korean ballistic missiles launched by Russia between late December and late February, as they seek to assess the threat from Moscow's cooperation with Pyongyang.
In previously unreported details of an investigation under way into the missiles, the office of Ukraine's top prosecutor, Andriy Kostin, also told Reuters that the failure rate of the North Korean weaponry appeared to be high.
"About half of the North Korean missiles lost their programmed trajectories and exploded in the air; in such cases the debris was not recovered," Kostin's office said in written answers to Reuters' questions.
North Korean missiles account for a tiny portion of Russia's strikes during its war on Ukraine, but their alleged use has caused alarm from Seoul to Washington because it may herald the end of nearly two-decade consensus among permanent members of the United Nations Security Council on preventing Pyongyang expanding its nuclear and ballistic missile programmes.
In addition to providing North Korea with an opportunity to test missiles, Russia has taken steps that will make it harder for the United Nations to monitor sanctions imposed on Pyongyang in 2006.
Last month, Moscow vetoed the annual renewal of the U.N. sanctions monitors - known as a panel of experts - that has for 15 years monitored enforcement of the U.N. sanctions on the Democratic People's Republic of Korea (DPRK), North Korea's official name.
China, one of the five permanent members on the Security Council with Russia, the United States, Britain and France, abstained from the vote.
Days before its mandate expired, the panel submitted a report confirming for the first time that, in a violation of U.N. sanctions, a North Korean-made ballistic missile known as Hwasong-11 had struck the Ukrainian city of Kharkiv.
This, and Moscow's veto, underscore how Russia and North Korea have intensified their bilateral relations beyond largely transactional, barter agreements, said Edward Howell, an expert on North Korea at Oxford University.
"There is a lasting legacy that is being shaped now, which is the fact that North Korea, through being assured of Russia's support, is really being able to undermine key international institutions like the U.N. Security Council," he said.
The Russian presidency referred questions on the North Korean missiles to the Russian Defence Ministry, which did not respond to emailed questions from Reuters. North Korea's mission to the United Nations in Geneva also did not respond.
DOZENS KILLED OR WOUNDED
Despite the setback at the United Nations, Kostin has said his office will carry on with the investigation.
The prosecutor's office said that when debris could not be collected at impact sites, Hwasong-11 missiles, which are also called KN-23 in the West, were identified by looking at their flight trajectories, speed and launch sites.
The last recorded use of a KN-23 was on Feb. 27, the prosecutor's office said, adding that the total number of launches it has identified tallied with intelligence showing North Korea delivered about 50 ballistic missiles to Russia.
According to the United States, Russia received ballistic missiles and artillery rounds from North Korea after the country's leader, Kim Jong Un, met Russian President Vladimir Putin for a rare summit last September.
The 21 cases, in which debris was collected, include three that were fired at the Ukrainian capital Kyiv and its surrounding region, Kostin's office said. The others struck the regions of Kharkiv, Poltava, Donetsk and Kirovohrad.
The attacks, which began on Dec. 30, 2023, killed 24 people, wounded 115 and damaged a number of residential buildings and industrial facilities, it said.
The about 50 missiles were launched from multiple sites including in Russia's western regions of Belgorod, Voronezh and Kursk, it added.
The Ukrainian statement did not say whether any of the missiles had been shot down by air defences. Ballistic missiles are typically hard to intercept because of their trajectory and speed.
According to Kostin's office, Ukrainian authorities were still investigating whether Pyongyang had dispatched instructors to monitor the ballistic missile launches.
(David Gauthier-Villars reported from Istanbul; Editing by Mike Collett-White and Timothy Heritage)