Russian President Vladimir Putin bragged earlier this year that his country had a new nuclear-powered missile with unlimited range — but it has yet to perform a successful test over multiple attempts, according to sources with direct knowledge of a U.S. intelligence report on the weapons program.

The cruise missile was tested four times between November and February, each resulting in a crash, according to sources who spoke to CNBC on the condition of anonymity.

The U.S. assessed that the longest test flight lasted just more than two minutes, with the missile flying 22 miles before losing control and crashing. The shortest test lasted four seconds and flew for five miles.

One report, according to the sources, did not mention health or environmental risks posed by damages to the missile's nuclear reactor.

The weapon, which has been in development since the early 2000s, is believed to use a gasoline-powered engine for takeoff before switching to a nuclear-powered one for flight, sources explained to CNBC.

The tests apparently showed that the nuclear-powered heart of the cruise missile failed to initiate and, therefore, the weapon was unable to achieve the indefinite flight Putin had boasted about.