Afghanistan marks 10 years since the start of the US-led war against the Taliban Friday amid heightened security and questions over what the next decade will hold.

Security is being stepped up in the capital Kabul after a string of major attacks including the assassination of peace envoy Burhanuddin Rabbani, which has thrown government strategy for talking peace with the Taliban into turmoil.

On the frontlines, it is likely to be business as usual for the 140,000 international troops in Afghanistan, of whom 100,000 are from the United States, as they continue the fight against a brutal, Taliban-led insurgency.

For many Afghans, the anniversary will be a time for reflection on what the war has meant for their country and how the withdrawal of all foreign combat troops by the end of 2014 will affect them in future.

"I spent a year in the city of Kabul during the Taliban regime and they made life difficult as they banned everything. We were forced to flee the country and live in Pakistan," said Abdul Saboor, a 30-year-old cook in Kabul.

"I was very pleased when finally the dark era of the Taliban ended in (our) country."

But Kabul street vendor Khan Agha, 30, highlighted discontent over civilian casualties and called for foreign troops to leave,

"Since the Americans and their allies came to Afghanistan, our security has deteriorated and they have also been involved in the killings of innocent Afghan civilians," he said.

A senior Afghan government official speaking on condition of anonymity to AFP said security would be stepped up for the anniversary.

"We do have some security measures," the official said.

"There will be more security, more checks. Police will be on high alert. But it's not going to be extraordinarily big measures -- there will be some preparations like more security and more checks."

Around 200 Afghans called for the withdrawal of foreign troops and shouted anti-American slogans at a protest in Kabul Thursday ahead of the anniversary.

They shouted "Death to America and its Afghan puppets" and torched an American flag at the end of their peaceful march through the city centre, an AFP reporter at the scene said.

The war was launched to oust the Taliban for harbouring Osama bin Laden, leader of Al-Qaeda which was behind the September 11, 2001 attacks in the US, and destroy Al-Qaeda training camps in Afghanistan.

On October 7, 2001, just under a month after September 11, American planes dropped dozens of cruise missiles and laser-guided bombs on strategic targets in Kabul and other Afghan cities.

That was followed by a ground campaign which defeated the Taliban within weeks.

Insurgents lay dormant in Afghan and Pakistani hideouts for the next few years, severely depleted by the invasion, and US attention turned to the war in Iraq.

But violence flared back up again around 2007 and 2008, prompting a surge in the number of troops sent to fight the Taliban -- the US alone sent 50,000 more.

As troops start limited withdrawals ahead of 2014, the Taliban have increasingly focused on launching targeted attacks against foreign forces as well as the Afghan military and officials.

The NATO-led International Security Assistance Force (ISAF) argues this shows it is winning the fight on Afghanistan's battlefields.

Figures from the United Nations indicate this year is on course to be the bloodiest yet for civilians, with 1,462 killed in the first half of this year, 80 percent by insurgents. ISAF insists it does all it can to minimise such deaths.

Experts argue that the 10th anniversary finds Afghanistan at a key turning point.

"Time is running out to leave Afghanistan in an acceptable shape that would justify the time, money, and lives spent in expanding the mission from counter-terrorism to state building," said Terry Pattar, senior consultant at defence intelligence group IHS Jane's.