Enlarge By Deshakalyan Chowdury, AFP/Getty Images Dutch soldiers of Charlie Air assault company check for unexploded bombs during a patrol in Chora valley in Afghanistan's southern Uruzgan province. By Deshakalyan Chowdury, AFP/Getty Images A DEADLY FEBRUARY A DEADLY FEBRUARY WASHINGTON  Attacks on U.S. and allied forces with makeshift bombs in Afghanistan are 50% more lethal than three years ago, reflecting insurgents' use of more powerful explosives and the increased vulnerability of troops who patrol more on foot than in the past. Lt. Gen. Michael Oates, director of the Joint Improvised Explosive Device (IED) Defeat Organization, told a House subcommittee that the casualty rate was "disturbing" and half that of troops hit by IEDs in Iraq. INTERACTIVE: A look at U.S. lives lost in Iraq, Afghanistan Overall, IED attacks have doubled over the past year in Afghanistan, Oates said. It was even worse when comparing February 2010 with February 2009, attributed in part to a Marine-led offensive in the town of Marjah in Helmand province. This year, insurgents planted 721 bombs compared with 291 last year. Those attacks killed or wounded 204 troops this February compared with 51 in February 2009. Oates cited several advantages Afghan insurgents had over U.S. forces: • Reliance on fertilizer-based explosives that lack metal components frustrates attempts to detect buried bombs. • U.S. forces traveling in heavy vehicles are forced to travel on the few improved roads in Afghanistan, making them easier targets. "This facilitates a successful enemy tactic of emplacing large explosive charges buried in the middle of the road or in culverts," Oates said. • The counterinsurgency strategy pushed by Gen. Stanley McChrystal stresses protecting Afghan civilians and requires troops to be in close contact with them. The downside, Oates said, is that "separated from the protection of an armored vehicle, they are also more vulnerable to casualty from an IED." Oates, in a USA TODAY interview, said winning the trust of Afghans will ultimately provide the best protection for U.S. troops. Afghans will identify insurgents and provide tips on where they have planted bombs. Oates said the military will focus on fielding new all-terrain Mine Resistant Ambush Protected vehicles designed specifically to protect troops in Afghanistan. Surveillance aircraft will monitor roads, troops will be trained to find and defuse bombs, and the networks that produce IEDs will be attacked. "There is no silver bullet," he said. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more