MOGADISHU, Somalia - The Somali government is preparing a major offensive to take back this capital block by crumbling block, and it takes just a listen to the low growl of a small surveillance plane circling in the night sky overhead to know who is surreptitiously backing that effort.

“;It's the Americans,”; said Gen. Mohamed Gelle Kahiye, the new chief of Somalia's military, who said he recently shared plans about coming military operations with American advisers. “;They're helping us.”;

That U.S. assistance could be crucial to the effort by Somalia's government to finally reassert its control over the capital and bring a semblance of order to a country that has been steeped in anarchy for two decades. For the Americans, it is part of a counterterrorism strategy to deny a haven to al-Qaida, which has found sanctuary for years in Somalia's chaos and has helped turn this country into a magnet for jihadists from around the world.

The United States is increasingly concerned about the link between Somalia and Yemen, a growing extremist hotspot, with fighters going back and forth across the Red Sea in what one Somali watcher described as an “;al-Qaida exchange program.”;

But it seems there has been a genuine shift in Somali policy, too, and the Americans have absorbed a Somali truth that eluded them for nearly 20 years: If Somalia is going to be stabilized, it is going to take Somalis.

“;This is not an American offensive,”; said Johnnie Carson, the assistant secretary of state for Africa. “;The U.S. military is not on the ground in Somalia. Full stop.”;

He added, “;There are limits to outside engagement and there has to be an enormous amount of local buy-in for this work.”;

Most of the U.S. military assistance to the Somali government has been focused on training, or has been channeled through African Union peacekeepers. But that could change. A U.S. official in Washington, who said he was not authorized to speak publicly, predicted that U.S. covert forces would get involved if the offensive, which could begin in a few weeks, dislodged Qaida terrorists.

“;What you're likely to see is airstrikes and Special Ops moving in, hitting and getting out,”; the official said.

Over the past several months, American advisers have helped to supervise the training of the Somali forces to be deployed in the offensive, though U.S. officials said that this is part of an continuing program to “;build the capacity”; of the Somali military, and that there has been no increase in military aid for the coming operations.

The Americans have provided covert training to Somali intelligence officers, logistical support to the peacekeepers, fuel for the maneuvers, surveillance information about insurgent positions and money for bullets and guns.

Washington is also using its heft as the biggest supplier of humanitarian aid to Somalia to encourage private aid agencies to move quickly into “;newly liberated areas”; and deliver services like food and medicine to the beleaguered Somali people in an effort to make the government more popular.

Whenever Somalia has hit a turning point in the past, the United States was there, sometimes openly, sometimes not.

In 1992, shortly after the central government imploded, U.S. Marines stormed ashore to help feed starving Somalis. In early 2006, when an Islamist alliance was poised to sweep the country, the CIA teamed up with warlords to stop them, and when that backfired, the U.S. military covertly supported an Ethiopian invasion.

Last summer, when Somalia's transitional government was nearly toppled by insurgents linked to al-Qaida, the U.S. government hastily shipped in millions of dollars of weapons.

Since then, the insurgents' imperative to retake the capital, and eventually other parts of the country, has grown, U.S. officials say, as al-Qaida has even considered relocating some of its leaders from Pakistan to here.

U.S. officials said several high-ranking Qaida agents are still active in Somalia, including Fazul Abdullah Mohamed, one of the suspected bombers of the U.S. embassies in Kenya and Tanzania in 1998, who is now believed to be building bombs for the Islamist insurgent group known as the Shabab.

The Somali government has tried limited offensives before and has failed, leaving much of the country in the hands of the Shabab, who have chopped off heads, banned music and brought a harsh and alien version of Islam to Somalia.

But officials say that this offensive, or at least the preparations for it, feels different. First, the government has the advantage of numbers, about 6,000 to 10,000 freshly trained troops, compared to about 5,000 on the side of the Shabab and its allies.

In the past six months, Somalia has farmed out young men to Djibouti, Ethiopia, Uganda, Kenya and even Sudan for military instruction and most are now back in the capital, waiting to fight. There are also about 5,000 Ugandan and Burundian peacekeepers, with another 1,700 on their way, and they are expected to play a vital role in backing up advancing Somali forces.

The government is also better armed and equipped. Parked in neat rows behind Villa Somalia, the president's hilltop villa in the center of Mogadishu, are newly painted military trucks, tanks, armored personnel carriers and dozens of “;technicals,”; pickup trucks with their windshields sawed off and a cannon riveted on the back of each one. The government also recently bought 10 Chevrolet ambulances.

There seems to be a qualitative difference, too. Somalia's forces are now led by Gelle, a colonel in Somalia's army decades ago who most recently was an assistant manager at a McDonald's in Germany. He is known among Somali war veterans as one of the best Somali officers still alive.

Many Somalia observers are confident that the offensive will push back the Shabab. The question is what will happen afterward. “;To take you need force, to hold you need discipline,”; said Ahmed Abdisalam, a deputy prime minister in the last Somali government. “;What's going to guarantee those troops don't turn on the population?”;

Or turn on themselves: many Somalis are worried the troops could split along clan lines, which is exactly what brought down Somalia's government in 1991. One lingering criticism of Somalia's president, Sheik Sharif Sheik Ahmed, is that he has been too holed up in Villa Somalia and has not engaged with local power brokers and played clan politics better.

Even though there is a new religious overlay to Somalia's civil war, with a moderate Islamist government battling fundamentalist Islamist insurgents, clan connections still matter and could spell success - or disaster.

That said, the government did recently strike a political agreement with a powerful moderate Islamist militia, which may join the offensive from the inland regions of the country. There has also been talk of a militia made up of Somali refugees living in Kenya advancing from the Kenyan side.