The military health system is running out of money for the fiscal year that ends Sept. 30 and may face a crisis if Congress does not immediately authorize an additional $900 million, according to defense officials.

The Pentagon's top health care administrators sent a letter to Congress on July 16 urging lawmakers to approve the request or, they wrote, "For the first time in several years ... we will run the real risk of exhausting funds needed to pay private-sector care costs in late July."

Halting payments to civilian doctors "could also have negative spillover effects in the direct care system ... with the potential of causing an adverse impact on operational support and readiness," the officials said.

The letter from defense health officials asks Congress to authorize the transfer of money from other areas of the military's massive budget, not to provide the Defense Department with a fresh infusion of new money.

The growth in health care costs is being driven in part by the rising cost of drugs obtained by beneficiaries through retail pharmacies, according to a copy of the letter obtained by Military Times.

A DoD spokesman downplayed the letter and said troops, military families and retirees should not worry.

"Military Health System beneficiaries should not be alarmed as there will not be disruptions or limitations in the care they receive," said Air Force Maj. Ben Sakrisson.

"The department has worked to reallocate already budgeted funds, and approximately $900 million would come from other department sources if the requests are approved by Congress."

For several years, the Pentagon has urged Congress to raise health care fees for retirees and for some military families as a way to absorb the soaring costs of providing health care. But Congress has refused and continues to keep Tricare premiums and other drug co-payments far below the levels of most civilian health insurance plans.