Amid a push by the Senate to vote on ending US support for the Saudi-led coalition waging war in Yemen this week, a new report indicates that American tankers have been refueling Saudi coalition jets with gas paid for by US taxpayers because of “errors in accounting.”

Millions of dollars have likely been drained from US coffers to support the Saudi-campaign, according to the report.

In the letter, one of the Pentagon's top attorneys acknowledges that free refueling services for the Saudi coalition cost more money than he could calculate. While one might think that someone at the 3 million-person organization that is the Pentagon would know exactly how much the US is owed, Castle said in the letter that the department is "currently calculating the correct charges."

The Pentagon reached its conclusion following an inquiry sent by Senator Jack Reed, a Democrat from Rhode Island who sits as the second most powerful member of the Senate Armed Services Committee.

Tens of millions of dollars is probably a decent estimate of how much US taxpayers have contributed to the Saudi campaign, according to The Atlantic.

A spokesperson from the Pentagon confirmed the letter's contents and its authenticity to the publication late last week.

A spokesperson for CENTCOM specifically said the command was "still working through the calculation" of how much the Saudi coalition has paid for the refueling services and jet fuel.

In other military finance news, the Pentagon failed its first-ever audit last month, as accountants found myriad discrepancies in the department's books that may take years to reconcile. "We failed the audit, but we never expected to pass it," said Deputy Secretary of Defense Patrick Shanahan.