Baghdad, Iraq ? U.S. Marines backed by British and Iraqi forces Tuesday launched a new offensive south of Baghdad aimed at wresting back control of the “Triangle of Death” from Sunni insurgents.

In dawn raids, about 5,000 Marines and British troops swept through the village of Jabella, about 50 miles south of Baghdad, in what amounted to a counteroffensive against a series of attacks launched by Sunni insurgents in the wake of the massive assault against Fallujah earlier this month.

The force, which included members of the 24th Marine Expeditionary Unit backed by recently trained members of an Iraqi SWAT team, captured 32 suspected insurgents, including a number of “high-interest individuals,” the military said.

The newest assault comes as Marines still are trying to restore basic services and hunt down isolated rebel holdouts in Fallujah, the former rebel stronghold that was retaken after eight days of bloody fighting.

With planned nationwide elections a little more than two months away, the U.S. military is under pressure to win back and secure dozens of insurgent-held neighborhoods, villages and towns across the Sunni Triangle, a broad swath of territory stretching north and west around Baghdad and including the so-called Triangle of Death just south of the capital.

Since October, U.S.-led forces also have attacked insurgents in Samarra and the northern city of Mosul.

Jabella, a poor desert village of date palms and farmhouses, is just one of a number of places clustered around the main highway just south of Baghdad that will be targeted by the latest offensive, the military said.

The area has long been referred to as the Triangle of Death because of the perils of passing through it. Insurgent activity there has increased sharply since the Fallujah offensive, suggesting that at least some of those who escaped Fallujah may have sought refuge in the desert region wedged between the Euphrates and Tigris rivers.

“Insurgent attacks rose in an apparent effort to divert attention from the high-profile battle west of Baghdad,” the military said.

The area targeted by the offensive includes four largely Sunni towns — Mahmoudiya, Latifiyah, Iskandariyah and Yusifiyah — whose location along the main highway linking Baghdad to the Shiite southern portion of the country gives the insurgents a virtual chokehold over travel between the capital and the south.

Those towns never were fully secured by U.S. forces in the aftermath of their dash to Baghdad last year, and their volatility has become an increasing impediment to efforts by the U.S. military and the government of Prime Minister Iyad Allawi to secure the country.

Black-masked gunmen wearing checkered scarves routinely man checkpoints along the main highway heading south out of Baghdad, stopping travelers and pulling out foreigners, anyone suspected of working for the government and, these days, ordinary Shiites plying the route between the capital and their religious shrines in the holy cities of Najaf and Karbala.

In the most recent incident, on Monday the bodies of 12 members of the Iraqi national guard were found at various locations near Latifiyah, one of the most feared towns in Iraq. Five of them had been decapitated.

Last week, insurgents blew up the bridge on the main highway, forcing travelers to pass through Latifiyah’s center, where insurgents more easily prey upon them.

The volatile area marks an informal divide between the largely Shiite south of the country and the mostly Sunni provinces to the north and west, and the targeting of Shiites risks heightening sectarian tensions ahead of the national elections Jan. 30. Shiites, who are a majority in Iraq, are enthusiastically planning for an election that would probably give them a leading role in government, while Sunni groups are threatening to boycott a poll they fear will end their long-standing dominance over the country’s politics.

Also Tuesday, a Sunni cleric was shot to death by gunmen in the second such attack on a cleric in two days. Sheik Ghalib Ali al-Zuhairi was killed as he left a mosque after dawn prayers in Muqdadiyah, 60 miles north of Baghdad, police told The Associated Press.

And in the central Iraqi city of Samarra, insurgents hit a U.S. convoy with a roadside bomb, prompting the Americans to open fire, killing an Iraqi, AP reported. Mortar rounds aimed at a nearby U.S. base injured two children.