WASHINGTON — Dispersed but not defeated, America’s Islamist enemies in Somalia could yet make a comeback, according to military and intelligence officials interviewed by The New York Sun.

Reports this week from Somalia’s capital suggest that the Ethiopian military has succeeded in breaking the grip of Somalia’s Islamic Courts Union in Mogadishu. But wire services yesterday also were reporting that the jihadists opted not to engage the better-armed Ethiopians, instead taking a cue from Iraq’s Islamist insurgency and blending back into the population when confronted with helicopter and tank fire.

The battle for Somalia is critical to America’s war on Al Qaeda. After a failed effort by America to support warlords and a transitional government in early 2006, the capital and south of the country fell to the Islamic Courts Union this summer, posing the specter of a new base for international jihad.

In particular America is worried about four people. To start, the deputy commander of the union’s military wing, Aiden Hashi Ayro, is said by American intelligence and a recent report by the International Crisis Group to have been trained in Al Qaeda camps in Afghanistan before September 11, 2001. After the attacks, he returned to Afghanistan to join the fight against the Americans.

Mr. Ayro’s boss and commander of the union’s military, Hassan Dahir Aweys, was placed on the State Department’s list of international terrorists in November 2001 and named in a presidential executive order the same month on international terrorism. American counterterrorism officials have long said Mr. Aweys was a key source of coordination for the 1998 Al Qaeda attacks on America’s embassies in Kenya and Tanzania.

Also of interest for America are Fazil Abdullah Mohammad, or Harun, and Abu Tala al Sudani, two alleged terrorists who helped plot the 1998 bombings and are now key leaders in the courts union.

In addition to the presence of Al Qaeda operatives inside the union’s military wing, the Treasury Department’s financial intelligence unit has tracked money from traditional Al Qaeda financiers in Saudi Arabia to the Islamic Courts Union accounts in East Africa. Al Qaeda leaders have urged fellow jihadists in recent videos and audio recordings to support the union’s fight against the transitional government and the Ethiopians.

Estimates of the strength of the Islamic Courts Union vary between 10,000 and 20,000 fighters. This week, Ethiopian commanders claimed to have killed 1,000 men. But one Western intelligence official said yesterday that it was likely that figure was inflated and that most of the terrorists fighting with the union had faded away.

“My assessment is that it is great the Ethiopians have experienced success in the army-to-army phase of the campaign,” a counterterrorism analyst, Daveed Gartenstein-Ross, said. “But it’s clear the Islamic Courts Union is preparing for guerrilla warfare. That’s why when the Ethiopians have moved into several towns, they find the ICU has already cleared out. All the while, the transitional government representatives do not think the insurgency can succeed.”

Earlier this week, the head of the executive council of the Islamic Courts Union, Sheik Sharif Sheik Ahmed, told reporters in Mogadishu that his fighters were planning an insurgency. “The fighting has now entered into a new phase. Since the Ethiopians are using heavy weapons, tanks and fighter jets and bombed on several locations, we have decided to order our fighters to draw back from the towns for military techniques,” he said. “Since we have no heavy weapons, we would start endless hit-and-run fighting against the Ethiopian invaders.”

Ethiopia’s prime minister, Meles Zenawi, promised yesterday that his forces would not remain in Somalia for long. He also said America, an ally of Ethiopia, “hasn’t contributed a single bullet, a single soldier, or a single military equipment to this operation.”

On December 4, the outgoing general in charge of America’s Central Command, John Abizaid, visited Addis Ababa for security consultations, a move regional observers have interpreted as giving the Ethiopians tacit approval for the military operation. America also helped to prevent a vote on an Arab League resolution at the United Nations this week that would have condemned Ethiopia’s escalation.