A new report has revealed that Russia is sending US and NATO weapons and equipment captured on the battlefield in Ukraine to Iran to be reverse-engineered.

In a report Friday, CNN cited four sources familiar with the matter as saying that Tehran has been trying to reverse-engineer the systems and probably produce similar ones.

According to the sources, US, NATO and other Western officials have seen several instances of Russian forces seizing smaller, shoulder-fired weapons equipment including Javelin anti-tank and Stinger anti-aircraft systems that Ukrainian forces have left behind on the battlefield.

In many cases, Russia has then flown the equipment to Iran to dismantle and analyze, likely so the Islamic Republic military can attempt to make their own version of the weapons, sources said, adding that Russia believes that continuing to provide captured Western weapons to Iran will incentivize Tehran to maintain its support for Russia’s war.

CNN report says US officials do not believe that the issue is widespread or systematic, and that it is not clear if Iran has successfully reverse-engineered any US weapons taken in Ukraine. The report added that since the beginning of the war the Ukrainian military has kept reporting to the Pentagon any losses of US-provided equipment to Russian forces.

Iran seems to be adept at developing weapons systems based on US equipment seized in the past. The Toophan anti-tank guided missile was reverse engineered from the American BGM-71 TOW missile, and the country also intercepted a US-made drone in 2011, a Lockheed Martin RQ-170 “Sentinel”, and reverse-engineered it to create a new drone.

The US is doing everything possible to counter the “burgeoning” military ties between Iran and Russia, the State Department said in February.