In arguing for a large force of U.S. troops to remain in Iraq after December [ “3,000 Isn’t Enough,” Sunday Opinions, Sept. 18], Sens. John McCain (R-Ariz.), Joseph I. Lieberman (I-Conn.) and Lindsey O. Graham (R-S.C.) claim, “Whether the United States has 3,000 troops or a larger force in Iraq will make no meaningful difference to our budgetary situation .” They also state that “no fewer than 10,000 and as many as 25,000 troops will be required .”

According to the Congressional Research Service, it currently costs an average of $802,000 to keep one U.S. soldier in Iraq for one year. At that rate, to keep 10,000 U.S. soldiers in Iraq from 2012 to 2021 would cost $80 billion; to keep 25,000 soldiers there would cost $200 billion. This $200 billion represents one-sixth of the $1.2 trillion target of the debt reduction “supercommittee.” It is also more than the government would save over 10 years if it were to cut the cost-of-living adjustment for Social Security and raise the Medicare retirement age to 67, as earlier discussed by President Obama and House Speaker John A. Boehner.

Robert Naiman, Washington

The writer is policy director for Just Foreign Policy.