BUCHAREST (Reuters) - Just how many troops does NATO need in Afghanistan? Despite repeated calls for more forces to be sent to fight Taliban insurgents, alliance leaders -- meeting on Thursday at a summit in Bucharest -- have been reluctant or unable to give a consistent figure for how many soldiers are required.
Adding to the confusion, NATO recently revised the number of soldiers it says it already has in Afghanistan -- adding some 4,000 troops in one fell swoop to give a total of 47,000.
French President Nicolas Sarkozy pledged in Bucharest to send a battalion -- some 700 troops -- to eastern Afghanistan. Other NATO leaders welcomed the move but no one suggested it would be enough to plug all the gaps in the force.
Precise troop figures are often hard to pin down because military planners think in terms of units and capabilities needed for a mission, rather than raw numbers of soldiers.
Units can vary greatly in size depending on their mission and which country is providing them. A U.S. Army brigade, for example, can have anywhere between 3,000 and 5,000 soldiers.
But the lack of clarity over NATO's Afghan mission goes beyond the vagaries of military mathematics.
It also reflects differences between what military doctrine suggests is needed in Afghanistan, what commanders would like and what NATO has approved as requirements.
The force is about three battalions short of the minimum outlined in an official document known as Combined Joint Statement of Requirements, NATO officials say. That translates into anywhere between 1,500 and 3,000 troops, they say.
U.S. Defense Secretary Robert Gates, who has campaigned strongly for more troops in Afghanistan, said this week that even achieving that minimum is "pretty ambitious."
But U.S. Army Gen. McNeill, the commander of the NATO-led force in Afghanistan, has a larger "wish list" amounting to an extra three brigades, Pentagon officials said.
Even that figure may not be what NATO really needs to succeed in Afghanistan.
McNeill has said U.S. doctrine suggests a force of well over 400,000 Afghan and foreign troops to fight an insurgency in a country of Afghanistan's size and population, although he has made clear he does not expect NATO to provide that.
While the lack of a clear target number of troops is a source of confusion, it also has an advantage for nations such as the United States pushing NATO allies to provide more forces -- they can always argue that the alliance must still do more.
Editing by Timothy Heritage