However, Bush admitted that the Iraq war launched on March 20, 2003 became "longer, harder and more costly than we anticipated".

"There's still hard work to be done in Iraq," he said, "The gains we've made are fragile and reversible."

He reiterated his opposition to fast withdrawal of the current 155,000 US troops from Iraq.

"We have learned through hard experience what happens when we pull our forces back too fast. The terrorists and extremists step in, they fill vacuums, establish safe havens and use them to spread chaos and carnage."

He said that he would wait for recommendation from top US commander in Iraq, General David Petraeus, and US Ambassador to Iraq Ryan Crocker, who will come to Washington to testify before Congress next month, before making any decision on the troop levels in Iraq.

The speech did mention the ballooning war budgets nibbling the US economy, the US private security guards' violence resulting in Iraqi civilian death, the controversial interrogation tactics raising human rights abuse charges and the conclusion in a newly-released defense intelligence report indicating no relationship between Saddam's regime and al Qaida.

A poll released by CNN on Wednesday presented a different picture of the Iraq war in US public eyes.

According to the poll, about 66 percent of the 1,019 adults surveyed opposed the Iraq war and 61 percent Americans said that troop withdrawal should begin in months after the inauguration of the new president next year.

It also showed that 71 percent of Americans blamed the war spending in Iraq for the country's economic woes.

Some US known economists said last week that the Iraq war would wind up costing US taxpayers about 3 trillion US dollars.