Warplanes in Afghanistan are dropping bombs and missiles on insurgents at about 25% of the rate they did three years ago despite more widespread combat, reflecting commanders' emphasis on reducing civilian deaths. So far this year, jets have dropped bombs on only 10% of their combat support missions, compared with almost 40% in 2007, Air Force records show. The decline coincides with the arrival of most of the additional 30,000 U.S. troops ordered to Afghanistan by President Obama. Attacks on U.S. and allied troops — as well as deaths — are at all-time highs. The reduction in bombing comes amid debate about rules restricting the use of overwhelming firepower for troops in combat. Some military analysts, including Barry Watts, who flew combat missions in Vietnam, say the rules have increased risk to ground forces fighting the Taliban. "My sort of gut reaction is that there is frustration about the rules of engagement," said Watts of the Center for Strategic and Budgetary Assessments. "It looks to me like it's gone a little too far in terms of limiting (civilian casualties)." Meanwhile, commanders, including Gen. David Petraeus, the top officer in Afghanistan, have said they will examine how the directives that govern the use of firepower, including airstrikes, are practiced in Afghanistan. Petraeus and other commanders have drawn a distinction between the rules, which are aimed at protecting civilians, and how they are implemented, suggesting that the review will focus on whether some commanders have placed too many restrictions on firepower. The rules are being reviewed to ensure troops don't misinterpret them and are able to use firepower when needed. Petraeus "wants to make sure that as we move forward with any adjustments, if there are any, that we continue to protect the Afghan civilians as much ... as we possibly can," said Lt. Gen. David Rodriguez, the No. 2 allied commander in Afghanistan. Still, Rodriguez said he was not aware of any incident in which airstrikes were denied when troops were in a tight spot. Eliminating civilian deaths can reduce attacks on coalition troops, according to a recent study by the non-partisan National Bureau of Economic Research. If two civilian deaths from a coalition attack could be eliminated, there would be six fewer violent incidents in the area in the next six weeks, the study showed. The report was done for commanders and briefed to top military officials. Military operations that alienate the public spur insurgents' recruiting and overall support, the study said. Marines often face the tension of protecting civilians while also fighting the Taliban. A Marine who loses a friend in a fight "will drop a bomb on any man," said Marine Col. Randall Newman, a regimental commander in Helmand province. Sometimes commanders have to hold the impulses of the Marines in check if civilians are at risk. So far, Newman said, the rules haven't hurt his ability to fight the enemy and firepower is used when appropriate. "I've got every tool in the toolbox and we use them when appropriate," he said. One complication, Newman said, is that the enemy knows the firepower restrictions, too, and incorporates that into its tactics.