The United States has asked Japan and Nato allies who have refused to send troops to Afghanistan to pay the estimated $17 billion needed to build up the Afghan army, according to US defence officials.
The push to quickly increase the size of Afghanistan's army and spread the cost of the initiative underscores the financial and military strain the war has placed on the United States and Nato members, many also operating in Iraq and elsewhere.
"The faster we get the (Afghan army) to the size and strength they need to be, the less they depend on us for providing security, and God knows we operate far more expensively than the Afghan national security forces do," said Pentagon press secretary Geoff Morrell.
"At a minimum it's going to cost $17 billion. That's a hefty price-tag and someone's got to pay it," Morrell said.
"This may be one of those cases where countries that have had a reluctance to contribute forces, in particular combat forces, may be able to take part in this mission through a financial contribution to the development of the Afghan National Army."
The new Pentagon push to share costs more widely reflects a realisation among US officials that some allies simply will not put troops into the war despite heavy pressure from Washington - something Europe has been telling the United States for more than a year. But it also threatens to create just the type of two-tiered Nato alliance that US Defence Secretary Robert Gates warned against early this year.
Gates in February said Nato risked a split between allies willing to "fight and die" and those who were not.
Morrell last week cast it as "those who fight and those who write checks." The Nato mission in Afghanistan will be discussed later this week at a meeting in Budapest. It will be the last Nato meeting of defence ministers during the Bush administration and Gates, who has repeatedly and publicly chided allies for two years to put more resources into the war, is expected to press the issue of cost sharing.
The meeting comes as the Bush administration conducts a comprehensive review of its strategy in Afghanistan, where security has steadily deteriorated despite a doubling of foreign troops over two years. Britain's commander in Afghanistan, in fact, has said the war against the Taliban cannot be won. US officials said Nato was not conducting any parallel review, although the senior commander has just submitted an updated and secret list of troop and equipment requirements.