Senior military figures reacting to the US casualties last night said the incident marked a moment to take stock of the coalition's presence in Afghanistan.
Major General Patrick Cordingley, a retired British army officer, said: "We must keep sight of the bigger picture and not just have an endless myopic presence in Afghanistan. That's not to say pull out immediately, but there must be strategic reasons for staying. The danger is that we can end up basing decisions on performances in certain regions, such as the Helmand province.
"It is also essential to manage expectations. It is important to be realistic and not just chase an illusion that may not ever materialise."
General Sir Hugh Beach, former deputy commander of British Land Forces, said: "This is a terrible tragedy. If these helicopters are being shot by RPGs, then it's symptomatic of a Taliban force that is either very lucky or being bankrolled to become even more sophisticated. Yet allied forces have to scale back methodically and strategically, not make reactive decisions. The Taliban have become deeply ingratiated in all areas of Afghanistan and it is difficult to predict where this is going, but we must stay the course."
Patrick Mercer, Tory MP for Newark and a former soldier, said: "If we were to look at the number of troop-carrying helicopters that the Soviets lost 20 to 30 years ago to enemy fire, these sorts of occurrences were regrettable but not that unusual. The Americans have just got unlucky.
"They've either got unlucky through pilot error or enemy action. However, you can't let this sort of thing influence the progress of US military operations. I have absolutely no doubt that the Americans will obviously mourn, but then crack on and put this down to the fortunes of war.
"There is nothing for this but to take it on the chin, mourn the dead and carry on. There may be an argument for ferrying smaller numbers of troops around in more helicopters, but obviously there is a practical argument against that in that they don't grow on trees.
"If the helicopter had come down with just the air crew on board, we would have hardly raised our eyebrows. The fact that it was fully laden with troops is just part of the fortunes of war. I deeply, deeply regret it, but we must not allow this to influence further military operations.
"It's extremely difficult to protect an aircraft from things like machine guns firing at helicopters which are fairly slow moving. But we've also got to protect ourselves from the Taliban's extreme capability with propaganda.
"No matter what we say and no matter what the inquiry into this finds, the Taliban will continue to claim that they brought this aircraft down."