WASHINGTON, Aug 25: The United States’ decision to start guarding Afghanistan’s President Hamid Karzai followed intelligence reports that Afghan warlords pose a direct threat to his life and authority, officials said on Sunday.

On Saturday, the State Department announced that its Diplomatic Security Service would take over Karzai’s security and would protect the besieged Afghan leader with the cooperation of US troops based in Afghanistan and private contractors.

The move reflects increasing concern in Washington that “Karzai is getting more and more isolated in his homeland,” as one US official said.

In recent months, US military officials in Afghanistan, have expressed new fears about the growing powers of the Afghan warlords. They say the warlords are not only undermining Karzai’s frail authority but are a threat to the overall US war strategy of eliminating the remaining Al Qaeda and Taliban pockets in southern and eastern Afghanistan.

Both Taliban and Al Qaeda operated mainly from the Pakhtoon-dominated areas in the east and the south before their defeat by US forces late last year and spread across the two regions afterward, creating small pockets among Pakhtoon populations.

To wipe them out and prevent future terrorist activities in these areas, the US officials urged Karzai to increase his support among the Pakhtoon.

They said Karzai was asked to head the new government - elected in June - because he is a Pakhtoon and the United States and its allies want him to earn the loyalty of the warrior Pakhtoon tribes.

The Americans also realized that Karzai would have to share power with other Pakhtoon leaders if he wanted to expand his support base. But the Northern Alliance, which dominates the new government and controls Kabul, the capital, did not permit Karzai to do this.

Fearing that the impasse could cause Afghanistan to slide back into chaos and violence, members of both parties in the US Congress are demanding that America take a more active role. The legislators’ feelings are shared by the Bush administration, with one official saying: “The problem is the war on terror is over, and what you have now are warlords fighting to save the local tribal structure and extend their power.”

In other words, support within Afghanistan for eliminating the Taliban has not translated into support for eliminating anti- western terrorism. Warlords given US military aid to help accomplish the first goal are now using those weapons, training and other support for their own aims, US officials have complained.

The Afghan Islamic Transitional Government, set up during the last session of the loya jirga on June 19, was to produce a coalition of forces that would bring about national reconciliation of various factions, but so far the regime has failed to achieve stability.

Another disturbing trend, according to the Bush administration officials, was Karzai’s replacement of qualified technocrats with warlords or their candidates. For example, Zalmai Rassoul, who had been civil aviation minister in the early days of the Karzai government, was replaced in June by Mirvais Sadiq, who is the son of the Shinbad warlord Khan.

Khan’s long-held ties to Iranian intelligence make him unpalatable to US policy-makers.

“He pretty much operates under the thumb of Iran,” said a former defence intelligence agency analyst, adding that Iranian military and intelligence experts are involved in training Khan’s men.