An intercepted letter from al-Qaeda's number two to its leader in Iraq warns insurgents' tactics may alienate the wider Muslim population, the US says.
Zawahiri is in hiding
The letter appeared to be from Osama bin Laden's deputy Ayman al-Zawahiri to Abu Musab al-Zarqawi, said Pentagon spokesman Bryan Whitman.
He did not show the letter or say how or where it was obtained, but said it was considered authentic and recent.
The missive warned that the network faced crises in many areas, he said.
"Zawahiri says that they've lost many of their key leaders and that they've virtually resigned themselves to defeat in Afghanistan, that their lines of communication and funding have been severely disrupted," Mr Whitman told reporters on Thursday.
'Must include masses'
The letter, said to be written in Arabic, was made public after the government learned of leaks to the media, US media quote officials as saying.
In the missive, Zawahiri apparently warns tactics such as the killing of hostages and bombings of mosques may alienate the "Muslim masses," Mr Whitman said.
"In this letter, he talks about believing that the eventual governance of Iraq must include the Muslim masses, and that they are at risk of alienating those," he told reporters.
The letter was also said to detail the strategy of Muslim extremists to create an Islamic state centred on Iraq that could expand into neighbouring countries.
Zawahiri included a plea for financial support, Reuters news agency quoted Mr Whitman as saying.
The New York Times quoted a senior official as saying that the 6,000-word letter was dated early in July, and was obtained by US forces involved in counterterrorism operations in Iraq.
In January 2004, the US authorities said they had intercepted a letter which confirmed that Zarqawi was working with al-Qaeda to drive the US out of Iraq. The authenticity of the letter was never confirmed beyond doubt.
Zarqawi's group has claimed responsibility for a series of killings, hostage beheadings and major suicide bombings in Iraq.
Zawahiri was number two - behind only Bin Laden - in the 22 Most Wanted Terrorists List announced by the US government in 2001. He has a $25m bounty on his head.
He was reportedly last seen in the eastern Afghan town of Khost in October 2001, and went into hiding after the US-led attack overthrew the Taleban.