US Defence Secretary Donald Rumsfeld, arriving on an unannounced visit to the Gulf, said on Sunday al Qaeda group were among insurgents launching deadly attacks in Iraq to spark civil war there.
But he vowed democracy would take root in the unsettled country despite current "untidiness".
Rumsfeld flew to Kuwait on Iraq's southern border - his fourth visit to the region since the US-led invasion of Iraq in March - and said attempts by "terrorists" to thwart elections in Iraq would fail.
"They clearly are involved and active," the secretary responded when pressed on whether al Qaeda, blamed for devastating 2001 attacks on America, were involved in Iraq. Pentagon officials said on Friday they had no proof any of the several hundred foreigners held in Iraq were al Qaeda members.
"We have seen information that terrorists are trying to foment strife between the religious and ethnic groups" in Iraq, he said.
The secretary refused in an interview with reporters flying with him from Washington to predict when elections might be held following a scheduled US turnover of authority to Iraqis on June 30. Paul Bremer, the US administrator in Iraq, has said elections could be delayed for 15 months.
"You have the normal untidiness of democracy where people say this and people say that. They discuss and debate and argue, and that's a healthy thing," Rumsfeld said. "My guess is it will not be perfectly predictable, as most democracies are not."
"Paul Bremer is working that (an election plan) with the President (George W. Bush) and all of us," Rumsfeld said.
"It is going along about as one would expect. You've got a country that has no experience with democracy through the adult lifetime of many who are there."
Rumsfeld spoke with reporters during an aircraft refuelling stop in Shannon, Ireland. He also shook hands with dozens of surprised US National Guard troops of the 120th Engineering Battalion from Oklahoma waiting in the Shannon air terminal while en route to Iraq.
The secretary declined to say whether he planned to visit Iraq during the Gulf trip. His previous visits have been cloaked in secrecy ahead of his arrival and he has moved about there under tight security protection.
Rumsfeld said the attacks in Iraq, which have killed hundreds of Iraqi civilians and civil workers in recent months, were not stopping the slow movement toward democracy.
"They are killing Iraqis and the Iraqi people don't like it. Instead of responding by acquiescing, volunteers are still in line to join the police. They are still in line to join the Army," Rumsfeld said.
The secretary said he had talked to experts on Friday who confirmed the authenticity of a computer disc found earlier in Iraq containing a letter which the United States says was written by Abu Musab Zarqawi, who Washington believes is a close associate of Osama bin Laden.
"The experts in our government believe that the letter is authentic," he said of the message outlining a plan for a series of attacks aimed at sparking a civil war in Iraq.
The US Army this month doubled its bounty for information leading to the arrest or conviction of Zarqawi to $10 million. The United States suspects him of links to Ansar al-Islam group operating in Iraq.