WASHINGTON – The top US military officer said Wednesday he sees an increase in bloodshed in Afghanistan as allied forces step up their offensive against the Taliban.

"As difficult as it may be to accept, we must prepare ourselves for more violence and more casualties in coming months," said Admiral Mike Mullen, chairman of the Joint Chiefs of Staff.

"The violence will be worse in 2011 than it was in 2010 in many parts of Afghanistan."

Mullen, who met with foreign journalists, said the United States along with 48 coalition partners and the Afghan army made gains against the Taliban in 2010, but added that "we know the gains we have made are tenuous and fragile."

"We know the enemy is resilient and we know the things are likely to get harder before they get any easier," he added.

"Now is not the time to rest on our laurels, it's the time to press on our advantages and to redouble our efforts."

Mullen noted that Taliban leaders have been eliminated or pushed out of sanctuaries in the southern province of Kandahar and Helmand in the southwest.

"The enemy is being pushed out of population centers, it's being denied sanctuaries and it's losing leaders by the score. Their scare tactics are being rejected by local citizens," he said.

"I have confidence it will to continue to lose so long as coalition and Afghan forces increase their presence and their pressure."

Mullen said the US expects to start a planned drawdown in forces this year but that the withdrawals "will be conditions-based." He declined to provide any new estimates for the US drawdown, which is expected to allow Afghan security forces to take over by 2014.

"The Afghan army is progressing in a much more organized and at a quicker pace than we have expected," he said.

The comments came at the end of the deadliest year in Afghanistan for US and NATO forces with 711 killed, according to the website icasualties.org.