A U.S. initiative to spend hundreds of millions of dollars on construction projects in Afghanistan, originally pitched as a vital tool in the military campaign against the Taliban, is running so far behind schedule that it will not yield benefits until most U.S. combat forces have departed the country, according to a government inspection report to be released Monday.

The report, by the special inspector general for Afghanistan reconstruction, also concludes that the Afghan government will not have the money or skill to maintain many of the projects, creating an “expectations gap” among the population that could harm overall stabilization efforts.

“Implementing projects that the Afghan government is unable to sustain may be counter­productive” to the U.S. counterinsurgency mission, the inspector general wrote. “If goals are set and not achieved, both the U.S. and Afghan governments can lose the populace’s support.”

The study calls into question a fundamental premise of the U.S. strategy to counter the Taliban insurgency — that expensive new roads and power plants can be funded and constructed quickly enough to help turn the tide of war — and it poses a sobering, counterintuitive question for policymakers in Washington: whether the massive influx of American spending in Afghanistan is actually making problems worse.

Many U.S. military commanders, diplomats and reconstruction experts have long believed that large infrastructure projects were essential to fixing Iraq and Afghanistan. Now-retired Gen. David H. Petraeus, the former top commander in both wars who is now director of the CIA, used to say that cash was one of his most important weapons.

But the latest report adds new weight to the argument — voiced by independent development specialists and even a few government officials — that the United States attempted to build too much in a country with limited means to assume responsibility for those projects. All U.S. combat forces are expected to be withdrawn from Afghanistan by the end of 2014.

Until now, most critiques have asserted only that the massive U.S. foreign assistance program has led to waste and fueled corruption. The new report goes further by suggesting that some projects may ultimately prove detrimental.

In a written response to the report, the U.S. Embassy in Kabul said it was “speculative” for the inspector general to conclude that some of the projects would have adverse effects. The top Pentagon official responsible for Afghanistan called the report premature and insisted that the announcement of the projects, even though they have not been completed, has generated goodwill and excitement among the Afghan people.

The inspector general’s examination focuses on the Afghan Infrastructure Fund, which was authorized by Congress in 2010 in part to prevent the Defense Department from dipping into a discretionary account for military commanders to bankroll large projects. The infrastructure fund was supposed to allow the Defense and State departments to collaboratively plan and pool money for large infrastructure improvements aimed at supporting the U.S. counter­insurgency campaign.

Since then, Congress has poured $800 million into the fund and the State Department has committed about $1 billion of its funds to related infrastructure programs.

Among the projects criticized by the inspector general is a plan to use costly diesel generators to provide electricity to residents of Kandahar, the country’s second-largest city, until the U.S. Agency for International Development and the U.S. Army Corps of Engineers install a new hydropower turbine at a dam in the violence-plagued hills of neighboring Helmand province. Purchasing diesel to run the generators, which produce about 25 megawatts of electricity each — enough to power about 2,500 Afghan homes or small businesses — is projected to cost U.S. taxpayers about $220 million through 2013.

Senior U.S. commanders argued that increasing electricity through the “Kandahar Bridging Solution” would be an important part of the overall American military effort to beat back the Taliban in Kandahar province. Those commanders asserted that more power to operate lights, television sets and fans would please residents and lead many of them to throw their support behind the Afghan government.

But other civilian and military officials have questioned that logic. When U.S. Army Maj. Gen. Kenneth Dahl was the deputy commander of U.S. forces in Kandahar last year, he said he could not find any evidence that the additional electricity was yielding greater employment, stability or support for the government. “This is a bridge to nowhere,” he declared to his staff in 2011.

Back then, Dahl also noticed a disturbing disparity: The installation of the turbine at the dam, which will not occur for at least two more years, will produce significantly less power than the city receives from the generators. Since the Afghan government will not have the financial ability to buy diesel for the generators, that means the city’s power supply will inevitably ebb once the turbine is operational and U.S. funding for diesel ends.

That gap was seized upon by the inspector general. “While the Kandahar Bridging Solution may achieve some immediate [counter­insurgency] benefits because — as stated by USAID officials — ‘people like having their lights on,’ the U.S. government may be building an expectations gap that cannot be met in a timely manner,” the report states.

The inspector general’s report also questions whether a new $23 million road in Helmand province will have adverse effects because the Afghan government has not compensated landowners for the destruction of their property. In addition, the report reveals that four electricity projects — costing a total of more than $300 million from the infrastructure fund — have not yet been awarded to contractors, despite claims from the military and USAID that they will have important counterinsurgency benefits.

Sen. Claire McCaskill (D-Mo.), a frequent critic of Afghan reconstruction efforts, said the report raises fundamental questions about the strategic rationale of U.S. development programs in the war-torn nation. “There’s no data that shows these major projects have changed the security environment in the country,” she said. “We cannot just throw money at a country like this and expect it to have a good ending.”

In its response to the report, the U.S. Embassy defended the importance of large-scale development initiatives. “These critical infrastructure projects have signaled to Afghan populations the U.S. government’s long term commitment to Afghanistan.”

Although the United States has spent almost $90 billion on Afghan reconstruction and development over the past decade, such examinations traditionally had not been conducted by the special inspector general’s office, which was more interested in contracting waste and fraud. This report was approved by a new inspector, former federal prosecutor John F. Sopko, who took charge of the office this month. He has vowed to scrutinize how projects are conceptualized and designed, not just how they are implemented.