In this remote, sun-blasted corner of southern Yemen, there’s a battle raging that is as important to the United States as it is to this nation’s beleaguered government.

Each day, American-backed Yemeni forces engage in a grueling struggle to retake territory from militant Islamists — a conventional army pitted against a guerrilla militia with grand ambitions to stage an attack on U.S. soil. Each day, the soldiers feel increasingly besieged.

“We are like an island in a sea of al-Qaeda,” said Lt. Abdul Mohamed Saleh, standing at a checkpoint on a desolate highway that connects Zinjibar with the port city of Aden. “We are surrounded from every direction.”

The battle is but one in a broader struggle that has upended Yemen over the past year and left the country badly fragmented. With pro-democracy demonstrators now in the 11th month of a populist uprising that has forced President Ali Abdullah Saleh to agree to step down, al-Qaeda in the Arabian Peninsula and its sympathizers have taken full advantage of the turbulence.

In May, they overran large swaths of Abyan province, including this regional capital. Today, they rule over significant territory in this strategic region, near important oil shipping lanes.

The al-Qaeda affiliate has already targeted the United States several times, including sending parcel bombs on flights into the country last year. Its stated goal is to create an Islamic emirate in Yemen, which American officials fear could be used as a base to plan more attacks against the United States.

That base may already be taking shape. A rare recent visit to Zinjibar, the first by a Western journalist since the Islamist fighters swept into the city, revealed just how entrenched the militants have become here.

An easy takeover

At the gate of the only military base left in this ghostly city, Ali al-Katib peered up and down the deserted road. Clutching a walkie-talkie and a Kalashnikov rifle, the Yemeni soldier looked as haggard as the battered landscape.

“They’ve attacked us three times already today,” Katib said, his emotions rising.

Saleh’s government has a mixed record of combating extremist groups. He is a nominal U.S. ally who has pledged to defeat al-Qaeda in the Arabian Peninsula, or AQAP. But critics say his government is primarily responsible for the instability that has allowed the group and other militant organizations to thrive.

Although the pro-democracy demonstrators have no sympathy for AQAP, the group is one of several regional forces that have seized on the chaos of the uprising to grab territory and power. Many fear that Yemen could face years of turmoil before a system emerges to unify the country.

In the north, Shiite Houthi rebels control three provinces. In the south, secessionist voices are growing louder. And in the divided capital, Sanaa, armed tribesmen and defected military units control entire neighborhoods, driven by fears that Saleh plans to hang on to power. His family and loyalists remain in control of the security forces and hold key government positions.

With Saleh’s government in disarray, the United States has stepped up operations against AQAP, using drone strikes to kill several of the group’s top officials, including Anwar al-Awlaki, the radical Yemeni-American cleric implicated in helping to motivate several attacks in the United States.

But such a strategy has its limits in Zinjibar.

Less than a mile from the highway stands Zinjibar’s main soccer stadium. Outside, a half-built apartment complex is riddled with holes from mortar shells. On a rooftop, soldiers peer from behind sandbags. Two tanks stand nearby. Inside the stadium, walls have crumbled from shelling; the artificial grass is littered with debris and bullets.

The Islamists emerged in March, taking over the town of Jaar and nearby areas. By the end of May, they had entered Zinjibar. They seized government buildings and looted banks and military depots.

Most troops, police officers and local officials fled Zinjibar, an ancient city that was once a major trading center with the Far East. Tens of thousands of residents fled as well, triggering a humanitarian crisis.

According to Yemeni military commanders and residents, the militants number only 700 to 1,000, and include fighters from Sudan, Somalia, Pakistan, Saudi Arabia, Iraq and Syria. Some wear long hair and thick beards. They call themselves Ansar al-Sharia, or supporters of Sharia — Islamic law. AQAP leaders said this year that they were operating under that name.

The ease of their takeover prompted Saleh’s critics to accuse him of purposely losing territory to convince the United States and Yemen’s neighbors that chaos would ensue if he were to step down. Opposition figures describe al-Qaeda’s presence in Abyan as exaggerated, a diversion by Saleh to remain in power.

But the soldiers of Brigade 25, who live inside the military base, have no doubts about their enemy’s identity. The only government forces who did not flee, they have been pummeled almost daily by mortars, rockets and snipers.

Wadhan Ali Said, a slim 20-year-old soldier, bears the scars of a sniper’s bullet in his back. He said he and his fellow troops lived on rice and well water for more than two months before U.S. planes dropped parcels of food into the base in September. On one day, the militants killed 10 soldiers inside the base, he said.

Later in September, after reinforcements arrived, the soldiers managed to lift the siege. But the militants have kept up the pressure, moving in highly organized cells. They use loudspeakers outside the base in a psychological assault on the soldiers.

“They say they are the followers of Osama bin Laden,” Said said. “They give us lectures on Islam. Then, they tell us they will enter the base tonight.”

Yemeni security forces have unleashed an intensive campaign of aerial bombings and shelling in southern Yemen. They have sent large numbers of reinforcements, including some U.S.-trained counterterrorism units.

Yet the Islamist fighters control more than half of this city, including its center. They dominate other parts of Abyan as well as neighboring Shabwa province, where they have imposed a strict interpretation of Islamic law. Al-Qaeda cells are also increasingly active in Aden, staging assassination attempts and suicide attacks.

Gen. Muhammad al-Somli, the commander of Brigade 25, said the United States has been assisting with intelligence. But his soldiers lack night-vision goggles, sniper rifles and other military equipment to adequately fight the Islamists. The U.S.-trained counter-terrorism units were too small in number, he said. And his soldiers, he added, are not adequately trained to combat a guerrilla force. He also acknowledged that the government has lost much of its control over southern Yemen to the Islamists.

“They are already acting like they are rulers of a state,” Somli said.

Reminiscent of the Taliban

The streets of Zinjibar are eerily quiet. Houses are abandoned, shops and gas stations closed. There’s no electricity. The landscape is silent, a wasteland littered with bullets and graves. Not a single resident was seen in more than four hours spent inside government-controlled areas of the city.

Most of the city’s inhabitants are 35 miles away, in Aden. They traveled with only the possessions they could carry. They have sought refuge there in dozens of schools, turning classrooms into makeshift homes.

But even Aden may not be safe.

“If we don’t manage to stop them, their next target will be Aden,” warned Brig. Awad al-Qatabi, the head of Yemeni National Security in the city.

Those who fled Abyan brought with them disturbing stories about life under the Islamists that are reminiscent of Taliban rule in Afghanistan. Drinking alcohol is punishable by death. Praying is mandatory and monitored closely by the militants. Television is banned, as is any contact with Westerners.

“Anyone who supports Saleh is considered an agent of America and the West,” said Salah Nasser Nashir, 34, a farmer, who fled in July.

He was more afraid of the indiscriminate bombings by security forces than he was of al-Qaeda, echoing comments by others who fled Zinjibar. “We fled not because of al-Qaeda, but because the government was shelling us,” he said.

Still others, though, fled the wrath of the Islamist militants. Maher Ali, 17, said he was caught two months ago stealing electric cables from a store. He explained to his jihadist captors that he was unemployed and hungry and that he needed money for food. They took him to a clearing. A man carried a bag of knives. They blindfolded Ali. A voice asked him which hand would he like to have cut off. Ali pleaded for mercy.

“This is Allah’s law,” he heard the voice say, before the knife came down on his left wrist.