The American-made Patriot missile system is likely responsible for the Russian Il-76 plane crash, American officials anonymously told The New York Times. The plane was also likely carrying at least some Ukrainian prisoners, officials reported.

Russia's Il-76 military transport plane crashed in the country's Belgorod region on Jan. 24, allegedly killing everyone on board.

The cause of the crash is unclear, with Russia claiming that Ukraine's military shot the plane down as it carried 65 Ukrainian POWs. Kyiv has demanded an international probe into the incident.

Ukraine's military intelligence agency did not confirm whether prisoners were on the plane nor have they commented on what might have caused the crash.

Ukrainian officials did reveal that a prisoner exchange had been planned for that day.

Ukrainian military sources told Ukrainska Pravda that the plane was carrying S-300 missiles, regularly used by Russia to strike Kharkiv Oblast.

The Patriot air defense system is a crucial component in protecting Ukrainian air space from Russian missile attacks.

Although American officials have been unable to confirm who was on the plane, sources told the NYT that it appeared probable that at least some of the passengers were Ukrainian prisoners.

The New York Times reported that American officials would not comment on what brought down the plane publicly. According to the news outlet officials who spoke privately on the condition of anonymity said that it was in fact the Patriot missiles.

After Russia claimed that 65 Ukrainian POWs were killed in the crash, Ukraine requested that Russia return the bodies of the killed POWs home.

Russia's government never responded to the appeal. Russia also reportedly blocked the International Committee of Red Cross from investigating the circumstances of the crash.

Officials report that Ukraine likely acted on weak intelligence as the plane was previously used to transport missiles, making it a valuable target for Ukraine's military.