The Pentagon says banning smoking would add to the stress for troops
American troops are not to be banned from smoking in war zones, the US Defence Department says.
The decision comes despite a recent study which recommended the US military should be tobacco-free.
Pentagon spokesman, Geoff Morrell, said US troops were already making enough sacrifices in Iraq and Afghanistan.
He said Robert Gates, the US defence secretary, did not want to add to the stress of the troops by taking away their right to smoke.
But Mr Morrell said the Pentagon would examine the recent study to see what else could be done to move towards banning tobacco in the military.
He said: "Obviously it is not our preference to have a force that is using tobacco products."
A report commissioned by the US government said last week that the US military should be smoke-free in the next 20 years.
The Institute of Medicine (IOM) said 30% of army personnel were smokers, leading to "very high" economic and health costs.
But it acknowledged that the change could be hard to introduce, as smoking had "long been associated with the image of a tough, fearless warrior".
The Pentagon has said it supports the idea and believes it is "achievable".
The report, commissioned by the Pentagon and the US Veterans Affairs Department (VA), said the Pentagon spent more than $1.6bn (£1bn) every year on tobacco-related medical care, hospital treatment and lost days of work.
It said that rates of tobacco smoking in the military had increased since 1998, and may be as high as 50% among service personnel returning from duty in Iraq and Afghanistan.