Months after top New York City officials expressed intense behind-the-scenes frustration at the security vulnerabilities at the United Nations headquarters in Manhattan, the U.N. is now planning to spend $100 million — donated by the U.S. — on the upgrade.

That has created a new controversy: critics want to know why the U.S. is footing the entire bill, and why that money is not being credited against U.S. dues for the following year.

“If the U.S. overpays the U.N., those funds should be returned in full to the U.S. Treasury,” declared Ileana Ros-Lehtinen, R-Fla., who heads the House Foreign Affairs Committee. “To allow the U.N. to redirect those U.S. taxpayer dollars for unrelated projects is unjustifiable.” Moreover, she says, “by allowing the U.N. to reap the U.S. surplus as a slush fund for construction, the State Department wants to stick U.S. taxpayers with 100 percent of the cost, instead of the 22 percent that the U.S. would be responsible for under normal procedures.”

Ros-Lehtinen is leading a charge in the House of Representatives Wednesday, with a bill that demands the U.N. refund not only the $100 million but the entire $179 million overpayment collected from the U.S. for the United Nations Tax Equalization Fund (TEF), an obscure financial device used to reimburse U.S. citizens who work for the U.N. for U.S. income taxes they pay. (The U.S. is the only major country to levy income taxes on U.N. salaries.)

Ros-Lehtinen calls the refund demand “a small step toward restoring sanity to our U.N. policy and government spending.”