Correction: An earlier version of this article misstated the cost of maintaining U.S. troops in Afghanistan as more than $10 billion a month. For March, that cost was estimated at $5.7 billion by the Defense Department and $6.7 billion by the Congressional Research Service. The CRS puts the overall cost of the war effort for fiscal 2011 at $118.6 billion. This version has been corrected.

The Obama administration sought Thursday to counter congressional skepticism of its expensive civilian aid programs in Afghanistan, saying the projects have “made a very big impact” and laid the groundwork for withdrawal of U.S. troops.

Development assistance is “the pathway that will allow us to have an effective reduction of our [military] presence,” said Marc Grossman, the administration’s special representative for Afghanistan and Pakistan.

The State Department was stung by a report, issued this week by the Senate Foreign Relations Committee, that questioned whether money spent to reconstruct Afghanistan’s economy, governance and other civilian sectors was accomplishing much, and whether the Afghan government was capable of maintaining the programs once it no longer receives massive infusions of foreign assistance.

The report, based on a two-year investigation by the committee’s Democratic majority staff, was released as the White House faces increasing pressure from lawmakers and the public to curb the costs of the Afghan war and speed the withdrawal of U.S. troops. The size of an initial troop drawdown, to take place by the end of July, is being debated within the administration.

Until this week, public and political attention had focused almost exclusively on the military price tag of more than $5 billion a month to maintain about 100,000 troops in Afghanistan. Speaking at a NATO meeting in Brussels on Wednesday, Defense Secretary Robert M. Gates acknowledged that additional savings could be found on the security side.

“Of course, there’s been a waste of money in Afghanistan,” Gates told reporters. “You show me a war where there hasn’t been a waste of money.”

Although Afghanistan is now the largest recipient of U.S. development assistance in the world, civilian aid expenditures — $19 billion since 2002 — have been a comparative drop in the bucket relative to military spending.

But the State Department and the U.S. Agency for International Development have traditionally been much easier targets for congressional budget hawks than the Pentagon. The Senate report provided a new opening for long-standing criticism of civilian foreign aid programs in Afghanistan and elsewhere.

In a State Department briefing, Grossman and USAID Administrator Rajiv Shah said the “surge” in civilian officials in Afghanistan authorized by President Obama — bringing the total to 1,130 — was as important a part of the president’s policy as the 30,000-troop surge he approved. The combined civil-military approach is a key tenet of the counterinsurgency strategy advocated by Gen. David H. Petraeus, the commander of U.S. and coalition troops there.

The Senate report challenged what it called “counterinsurgency theory,” saying that such military-tied “stabilization” efforts in combat zones are likely to be short-lived and unsustainable in the long term. It also criticized the extent to which U.S. and other foreign funds are spent directly on major projects by outside contractors, rather than being funneled through the Afghan government.

Shah said that “we do endorse some of the basic findings” of the report, including calls for better oversight and multi-year congressional funding that would eliminate an emphasis on spending money fast, before Congress can decide to cut it in subsequent budget cycles.

But Shah said that many of the report’s recommendations were already being addressed, and he disputed its assessment of little progress in overall reconstruction in Afghanistan.

Afghanistan’s economy has grown by about 10 percent annually in recent years, Shah said, and 38 percent of U.S. aid now goes through Afghan institutions. He cited various initiatives that have increased the number of Afghan children in school, from 900,000 — all boys — under the Taliban government ousted in 2001 to 7 million — including 2.5 million girls.

“We see results every day,” Shah said, with “some of the most dramatic gains in life expectancy, infant mortality” and other health statistics. “These are linked very closely to the expenditure of U.S. resources,” he said.

“Work in Afghanistan is obviously more difficult than elsewhere,” he said. “A war is going on” and the civilian “staff take great risks. . . . We are under no illusions about how challenging it is.”

Staff writer Craig Whitlock contributed to this report.