Deadly attacks on US forces in Iraq have so far been the work of disparate insurgents, but anger at the US-led occupation could spark broader resistance.
"It's not yet a guerrilla war," said Mustafa Alani, an Iraqi analyst at London's Royal United Services Institute (RUSI).
"There is no central control, it's not a unified movement and the attacks are concentrated in the western part of Iraq," he said.
This partly chimes with the views of General Richard Myers, chairman of the US Joint Chiefs of Staff, who said at the weekend that resistance was fragmented and restricted to a Sunni Muslim triangle from Baghdad to the north and west.
He identified five groups behind assaults that have killed 29 US soldiers since President George W. Bush declared major combat over on May 1, three weeks after former Iraqi president Saddam Hussein's fall.
These were Saddam loyalists, foreign fighters from Syria and Iran, the Ansar al-Islam group said to be linked to al-Qaeda, criminals freed by Saddam before the war and Sunni extremists.
Analysts agreed the resistance was fractured, but said US officials, at least in public, were understating the growing resentment of many Iraqis at the unsubtle tactics of American troops grappling to impose control in a postwar power vacuum.
"I see this as Somalia writ large," said Jonathan Stevenson, an American counter-terrorism expert at London's International Institute for Strategic Studies.
"So far atomized groups are becoming increasingly hostile to the American occupation," he said.
Much more is at stake for the US in Iraq than in Somalia, where a US relief mission ended in disaster in 1993 after 18 US troops were killed in a firefight with militiamen.
Stevenson said the Americans were meeting a "creeping but rather strong nationalism" in Iraq, where they were failing to deliver on perceived promises to improve living conditions and hand the country back to Iraqis after 35 years of Baathist rule.
US firepower could suppress any direct military challenge from what he described as a nascent insurgency, but this would not produce the stability the Americans sought.
"They need a political solution that vindicates the war and wins the peace. They're still groping for how to do that," he said.
Stevenson said there was no solid indication yet that al-Qaeda or other "transnational terrorists" were meddling in Iraq, but argued that the US presence there was a tempting target.
"Even if they haven't yet penetrated Iraq, they would like to do so and hook up with indigenous Islamists there," he said.
US administrator Paul Bremer has said patience is needed to rebuild a shattered country, but time is not on his side.
"If the political failure continues, along with the difficulty in providing services, the economic crisis, the problem of the Iraqi army, some sort of organized resistance movement could develop into guerrilla warfare," Alani said.
He said US troops had made serious blunders, notably in the town of Falluja, west of Baghdad, where he said anti-US attacks had begun as revenge for the killings of 15 youthful demonstrators by American forces in late April.
Alani said the Americans should have made amends in line with the Sunni town's tribal, conservative traditions by sending mediators to apologize, pay blood money and perhaps promise to build a new school in memory of the dead youngsters.