U.S. troops in Afghanistan go "outside the wire" knowing they'll be rescued if they get hurt in a shootout.
"We don't walk out of our [Forward Operating Base] unless we have the confidence that if we're wounded, we have someone there who can help care for us and evacuate us back to the next level of treatment," said Army Gen. Martin Dempsey, the chairman of the Joint Chiefs, while speaking at a lunch with reporters in April.
"That is a key factor in how confident they will be."
The fledgling Afghan security forces have enjoyed knowing for more than a decade that an allied helicopter is only a radio call away. But when the U.S. pulls most of its forces from Afghanistan in the coming months, those calls will increasingly go unanswered.
The allied International Security Assistance Force has been working feverishly in recent years to build up the Afghan military's ability to evacuate its wounded back to hospitals.
It has trained local pilots and purchased Russian-made Mi-17 helicopters, which operate at Afghanistan's higher altitudes better than the American UH-60 Black Hawk.
Afghans have become proficient at ground-borne evacuations, but still rely on American evacuations when they get into a jam: A CASEVAC is an aircraft that is not dedicated to transporting wounded fighters, and usually does not have medical personnel on board. A MEDEVAC is comparable to an ambulance, where specially trained crews can keep wounded troops alive long enough to get back to a field hospital.
Afghan National Security Forces will likely only be able to take on CASEVACs in the coming years, and that capability is still shaky.
"I can't emphasize enough how important it is to get these right," said British army Brig. Gen. Stuart Skeates. "That work is now the absolute exclusive focus of RC-Southwest."
Skeates is the deputy commander for the U.S. 1st Marine Expeditionary Force-Forward which in February returned from notoriously violent Hellmand province in the Taliban heartland. He emphasized the same point that Dempsey makes in giving troops the necessary confidence to forge into dangerous territory.
"A decent medical capability will increase their confidence and their willingness to do that," he told reporters at a breakfast meeting in April. "Despite the fact that their medical capability is at a fairly immature stage, there is no sign of a lack of willingness to get out there day to day and fight the enemy."
He added that injuries are in no way impeding the Afghans' willingness to "get out there and take on the insurgents."
That point remains the key variable as the U.S. plans to pull out all combat troops by the end of 2014. The White House has yet to release how many forces it expects to keep in Afghanistan in pure support role, such as conducting MEDEVACs or training and advising. The top U.S. general in Afghanistan says ISAF already does not have enough capability to provide the Afghan military all it asks for.
Many Afghan watchers say the success of the nearly 13-year war hinges on how many troops the U.S. decides to keep in the country after the 2014 withdrawal date. U.S. allies, in turn, will also provide a proportionate number of their own troops to stay behind.
Critics say fighters in the Afghan army will drop their weapons and doff their uniforms at the first sign that the U.S. might not be there to support them.
"You can be a pretty dedicated fighter who also needs to feed his family," says John Nagl, a retired Army officer credited with co-writing the Army and Marine Corps manual for fighting a counter-insurgency in Afghanistan.
"If we cut off their pay, I don't know how long they would stick around, and frankly I wouldn't blame them," he tells U.S. News. "I can't tell you how many American troops I know who live paycheck to paycheck."
Air support and the ability to provide combat evacuations are hinged on one another, Nagl says.
"The U.S. is better than anybody in the world at providing these resources," he says. "They are expensive, complicated, technologically demanding, and the ANSF are going to have a hard time delivering [them]."