Updated

American and British forces poised to assault the Taliban stronghold of Marjah, in Afghanistan's southern Helmand province, have begun targeting insurgent leaders for assassination, The Sunday Times reported.

Special forces have been infiltrating the town on "kinetic" missions — jargon for armed attacks.

"Special forces guys have been going in on assassination missions with the aim of decapitating the Taliban force," a military source told the Sunday Times.

At U.S. Marine base Camp Leatherneck and the adjoining British base of Camp Bastion, troops and munitions have been airlifted in by night to avoid enemy rockets. In a break from traditional military secrecy, American, British and Afghan commanders have revealed that Marjah, the last town in Helmand under Taliban control, will in fact be the site of fighting in the near future.

Though Operation Moshtarak —Operation Together — has been widely publicized by top military leaders, the timeline for the offensive has not been revealed.

The success of the planned campaign depends on how quickly troops and civilian development workers can get public services up and running once the Taliban have been driven away, the top U.S. and NATO commander said Sunday.

The military has widely publicized the upcoming offensive in Marjah — the biggest Taliban-held community in the south — although the precise date for the attack in Helmand province remains classified.

Gen. Stanley McChrystal said the element of surprise is not as important as letting Marjah's estimated 80,000 residents know that an Afghan government is on its way to replace Taliban overlords and drug traffickers.

"We're trying to create a situation where we communicate to them that when the government re-establishes security, they'll have choices," McChrystal said.

Establishing functioning government has been messy even in the relatively safe parts of Afghanistan. NATO forces and international diplomats have to balance the need to increase security with the desire to build up Afghan institutions that have too-often been corrupt or ineffective.

Click here for more from the Sunday Times.

The Associated Press contributed to this report.