Chuck Hagel, a Republican senator said: "I think this speech given last night by this president represents the most dangerous foreign policy blunder since Vietnam, if it is carried out".
|"I believe the president's strategy is ... a tragic mistake"|
Joseph Biden, US senator, Delaware
Joseph Biden, the senator who presided over the committee's inquisition, said Americans' prayers for a workable strategy had not been met.
"I believe the president's strategy is not a solution, Secretary Rice. I believe it's a tragic mistake."
"The result will be the loss of more American lives and our military stretched to the breaking point with little prospect of success."
Anti-war activists took to the streets of US cities on Thursday for the first of what organisers promised would be thousands of protests against Bush's plan to send more US troops to Iraq.
Jan Rogers, 58, who took part in a protest in San Francisco, said the president "doesn't seem to get it".
"The rest of the country is shouting, 'Stop this insanity,' and I think he's just trying to save his presidency and his legacy. But he's just on the wrong path."
|Protesters demonstrated against Bush's plan|
to send more troops to Iraq [AFP]
Law student Zahra Billoo, 23, advocated an immediate troop withdrawal.
"I think our only presence at this point needs to be humanitarian aid. No more armed soldiers - they're not wanted there."
In New York, Tony Palladino protested in Lower Manhattan's Foley Square with a pair of anti-war signs. The former Air National Guardsman said the new troops would just give Iraqi fighters "20,000 extra targets".
Rallies were also planned in Boston and some other cities.
In Times Square, hundreds of anti-war protesters crammed onto a traffic island, chanting "Stop the funding, stop the war" as drivers in one of the world's most famous intersections honked in support.
Anti-war activists have marshalled more than 100,000 protesters at US rallies on a few occasions since the run-up to the Iraq invasion. But the vast majority of demonstrations have been far smaller than those of the Vietnam era.
"Bush's strategy has failed totally in Iraq and USA has already lost the war. The new plan will not work; it will only bring more deaths and make things in Iraq worst..."
Dimos, Hania-Crete, Greece
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Robert Gates, the defence secretary, said no one could predict how long the US troop increase in Iraq would last.
"It's viewed as a temporary surge, but I think no one has a really clear idea of how long that might be," Gates said, adding the United States would closely monitor Iraqi compliance before the first new troops arrived in Iraq.
He also warned that all districts would be targeted, including the stronghold of Shia leader Moqtada al-Sadr, while Rice vowed the United States would not let Tehran disrupt the US plan to stabilise Iraq.