WASHINGTON (AFP) - Taliban snipers have emerged as a lethal threat to US troops waging an assault in southern Afghanistan, as their bullets can penetrate American helmets, the US Marine Corps commandant said. Homemade bombs, or improvised explosive devices, have been the number one killer of NATO-led troops in the Afghan war but General James Conway told lawmakers on Wednesday that snipers pose an equally serious threat to coalition troops fighting an offensive in the Marjah area of Helmand province. Right now, the biggest threat in Marjah is not necessarily the IEDs for our killed in action, it is the sniper that take a long range shot and can penetrate our protective equipment, particularly the helmet, Conway told the House Armed Services Committee. He said the Marine Corps was pressing the defense industry to come up with a better helmet that could withstand a 7.62mm round from the AK-47 assault rifles favored by the insurgents. So we continue to pound the table on that with hopes that one day well have that piece of gear in hand, Conway said. In announcing the deaths of troops in the Afghan mission, the Pentagon does not specify if a soldier or Marine has been killed by a sniper. But it has cited small arms fire as the cause of death in numerous cases in the Marjah assault. About 15,000 US, Afghan and NATO forces launched Operation Mushtarak