The Pentagon overestimated the value of the ammunition, missiles and other equipment it sent to Ukraine by around $3 billion, a Senate aide and a defense official said on Thursday, an error that may lead the way for more weapons being sent to Kyiv for its defense against Russian forces.

The error was the result of assigning a higher than warranted value on weaponry that was taken from U.S. stocks and then shipped to Ukraine, two senior defense officials said on Thursday.

"We've discovered inconsistencies in how we value the equipment that we've given" to Ukraine one of the senior defense officials said. The officials and the Senate aide spoke on the condition of anonymity. Congress is being notified of the accounting adjustment on Thursday, the sources said.