The KC-46 tanker program faces potential budget issues that could force a renegotiation of the Defense Department’s contract with Boeing, according to budget analysts.

The program, considered a future cornerstone of the Air Force, is being squeezed by both current funding levels and a potential sequester.

DoD planned to spend $1.8 billion on the tanker program in fiscal 2013. However, Congress has failed to pass a new budget, leaving programs funded under a continuing resolution that leaves financial support at 2012 levels. For the KC-46 program, that means making do with just $900 million, or half of what the program office had planned for this year.

That presents a major problem for the aerial tanker program, said Todd Harrison, a budget expert with the Center for Strategic and Budgetary Assessments.

The KC-46 is particularly vulnerable, Harrison said, because it is still in the development stage, where budgets are slated to ramp up significantly year to year. But there is also concern that spending cuts could force the government to change a contract that is considered very friendly to the Pentagon.