WASHINGTON — Defense Secretary Ash Carter blasted a House budget plan to drain the Islamic State war fund in 2017 to pay for more troops, training and new equipment.

In a blistering letter issued Thursday, Carter warned the chairman of the House Armed Services Committee that the use of war money for base budget spending is his “most urgent concern” because it could cause funding for troops fighting overseas to run dry in April.

The secretary also renewed a veto threat that has hung over the House plan since it was unveiled earlier this year.

“By gambling with warfighter funds, the bill risks the safety of our men and women fighting to keep America safe, undercuts stable planning and efficient use of taxpayer dollars, dispirits troops and their families, baffles our allies, and emboldens our enemies,” Carter wrote to Rep. Mac Thornberry, R-Texas, chairman of the Armed Services Committee.

Congress has painted itself into a corner with the defense budget by passing mandatory federal spending cuts. The House plan crafted by Thornberry and his committee attempts to skirt the limits on defense spending by pulling $18 billion from the overseas war fund – a pot of money exempt from the mandatory cuts -- and using it to pay for what Thornberry says is a growing gap in training, aircraft and ships.

Thornberry and the House Armed Services Committee did not immediately respond to requests for comment Friday.

Carter and President Barack Obama’s administration have called the plan a gamble and a gimmick because it will cause the U.S. war efforts in Iraq, Syria and Afghanistan to run out of money at the end of April, forcing Congress and a new president to cobble together new spending or face shutting down operations.

“My first and most urgent concern is that the House bill fails to provide our troops with the resources they need to fight our enemies around the world and keep our nation safe,” Carter wrote in the letter to Thornberry.

However, shifting the money holds some appeal for rank-and-file servicemembers as well as Republicans worried about anemic defense spending. It would allow the House to dole out the largest servicemember pay raise in recent years and would reverse an Army drawdown.

Troops would get a 2.1 percent raise, which equals an additional $48 per month for an E4 with three or more years of experience. Last year, Obama ordered a 1.3 percent raise, keeping in line with increases that have been below private sector wage growth since 2011.

Meanwhile, the Army has proposed cutting 15,000 soldiers during the coming year and the House plan would freeze that reduction and instead add another 5,000.

Overall, the $18 billion would be plowed into higher troop levels, more training, military facility improvements, and repairing and buying new equipment.

The spending plan is part of the $602 billion National Defense Authorization Act passed by the House in May. The Senate has also passed its version of the annual budget bill but it does not call for draining the war funds.

Carter’s criticism comes just as the House and Senate prepare to hammer out a compromise NDAA bill that must choose between Thornberry’s $18 billion shift and the more conservative spending plan put forward by senators.

The secretary said he is “hopeful” that the lawmakers will reject using the war funds. A final budget bill will not be ready until after Labor Day, when Congress returns from a long summer recess.

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