American military officials believe that Taliban fighters are preparing to launch an offensive against the US and its Afghan allies this spring, according to a media report.

Quoting a senior US military official, Time magazine said that at the same time US forces would mount a spring offensive of their own, in tribal areas along the borders of Afghanistan and Pakistan, to flush out Osama bin Laden.

"As the weather gets better and as people are better able to travel in the rougher terrain, we expect an increase in violence," General Richard Myers, Chairman of the Joint Chiefs of Staff, said.

The US is not expected to openly announce the true intent of the offensive, which will focus on an area stretching from Jalalabad, near Afghanistan's eastern border, to Kandahar, a former Taliban stronghold in the south.

While the US pushes east along a broad front, Pakistani forces will push west, flooding the tribal areas in what Lt General David Barno, commander of US-led coalition forces in Afghanistan, calls a "hammer and anvil" strategy.

A small contingent of special operations troops taken out of Afghanistan for the war in Iraq, including members of the Elite Joint Task Force 121, which helped track down Saddam Hussein, will be reinserted for the offensive, Time said quoting the official.

The US military, Time said, is spending $900 million a month on Afghan operations, in contrast to $4 billion a month in Iraq.

While US soldiers in Iraq are dying at a rate of one a day, in Afghanistan the US suffers an average of one casualty a week.

In interviews with Afghans, diplomats and military commanders across the country, the magazine found that Afghans' daily lives still remain blighted by violence and fear. Forces loyal to Taliban leader Mullah Mohammed Omar -- believed to be hiding in Afghanistan or Pakistan -- now control nearly one-third of the country's territory.

"If we left," a US official told Time, "Karzai [Afghanistan president] would be dead within days."

Hamid Karzai, Time said, is lonely. He is huddled, as always, deep inside his presidential palace in Kabul, protected by towering stone walls, growling dogs and US bodyguards.

Visitors to the palace must undergo three separate body searches before passing through the arched gates, all under the gaze of trained marksmen standing sentry in a watchtower.

Because of the paltry number of foreign peacekeepers -- about 20,000, in contrast to 130,000 troops in Iraq -- and Karzai's inability to extend his grip outside Kabul, most of Afghanistan is under the sway of truculent warlords who in many cases finance armed militias through a resurgent opium trade.