The US military in Afghanistan says it has begun a new operation against Taleban and al-Qaeda militants, ahead of elections planned for next year.
The Taleban still carries out attacks in Afghanistan
A US army spokesman said the offensive, known as Operation Lightning Freedom, began after last Tuesday's inauguration of President Hamid Karzai.
All 18,000 troops in the US-led force would be involved, he said.
Analysts say the offensive also aims to persuade Taleban militants to accept a recent US amnesty offer and disarm.
Operations and aid
The US military says the aim of the operation is to boost security ahead of parliamentary elections planned for the spring - although correspondents say few believe they can happen before next summer.
The BBC's Andrew North in Kabul says it is not clear whether the campaign will mean any real change in tactics by US forces in the eastern and southern provinces where the Taleban and other militants are concentrated.
In a briefing, the US spokesman said they would continue to mix combat operations with aid to remote communities - an approach they have followed for the past year.
US commanders say the amnesty initiative is starting to work, although they have not provided evidence, our correspondent notes.
In the long run they hope it will bring the Taleban-led insurgency in Afghanistan to an end, allowing them to withdraw troops to help out in Iraq, our correspondent adds.
The new operation follows Operation Lightning Resolve, a
security operation to protect October's presidential election.
The Taleban were ousted in late 2001 when US forces invaded Afghanistan following the attacks on the World Trade Centre in New York.
The Taleban had given sanctuary to Osama Bin Laden and members of his al-Qaeda network, who are accused of carrying out the attacks.