AMERICAN military chiefs believe that the global war against terrorism will last at least six years.
Pentagon officials are being advised to draw up budgets and plans to buy new equipment on the assumption that the struggle against al-Qa'eda and other international terrorist groups will endure until 2008, and perhaps even longer.
Donald Rumsfeld, the defense secretary, has won President Bush's backing for a sharp increase in military spending.
Extra money will be allocated for more of the weapons that have proved useful in Afghanistan, such as unmanned surveillance and attack aircraft.
The increased spending will continue whether or not Osama bin Laden is found soon.
It follows signs that the Pentagon is wearying of the intense public interest in the hunt for the al-Qa'eda leader, and Mullah Omar, the Taliban leader.
John McCain, a senator and former chairman of the armed services committee, said on his return from a trip to the Afghan region that he felt frustrated that bin Laden was still at large.
He added, however: "He's on the run now. I think he's a threat so long as he's alive, but it's a far different scenario than the one where he had sanctuary and was able to operate with a financial network and a network of terrorists throughout the world."
After four weeks in which the Pentagon and the media were constantly on tenterhooks for the imminent capture of bin Laden, a change of tack ordered by Mr Rumsfeld has become evident.
Officials say that they will no longer even hint at where they think he might be.
There have also been reports of clashes between the Pentagon and the CIA over the quality of intelligence emanating from Afghanistan.
Some military officials feared there was a "missed opportunity" when the Pentagon ordered US Central Command to rely on local Afghan forces rather than US troops to try to intercept and capture bin Laden after the assault on al-Qa'eda's Tora Bora mountain hideouts.
Not only did bin Laden apparently escape, but so have a series of Taliban leaders over the past two weeks, almost certainly including Mullah Omar, raising questions about the competence or possible corruption of the Afghan forces.
Although no politician is yet prepared to risk publicly differing with Mr Bush over the administration's handling of the war, some advisers fear that public patience over the failure to catch bin Laden will evaporate if the hunt drags on too long - or if there is a fresh terrorist attack on the US.
© Copyright of Telegraph Group Limited 2002