biggest military disasters
in support of keeping troops in Iraq.
"One unmistakable legacy of Vietnam
is that the price of America's withdrawal
was paid by millions of innocent
citizens in 'killing fields.'"

That's it, George, Chin out, try to bluff with your dismal hand
making explicit references to Vietnam
It is a gamble, risking reminding Americans
that Vietnam was a military quagmire
and reminding them of the shambolic retreat
from the embassy rooftop in Saigon
But Bush tried to turn the argument round
as he made a series of contentious political parallels
Bush gambles with Vietnam reference over Iraq
Bush sought to buy more time for his Iraq "surge" strategy today by making a risky comparison with the bloodshed and chaos that followed the US pullout from Vietnam.
Making it clear he will resist Congressional pressure next month for an early withdrawal, he signalled US troops will be in Iraq as long as he is president and said the consequences of leaving "without getting the job done would be devastating".
Mr Bush's speech came on the day that the US suffered one of its highest daily death tolls since the 2003 invasion, with 14 troops killed when a Black Hawk helicopter crashed.
In a speech to army veterans in Kansas City, Mr Bush invoked one of America's biggest military disasters in suppport of keeping troops in Iraq.
"One unmistakable legacy of Vietnam is that the price of America's withdrawal was paid by millions of innocent citizens whose agonies would add to our vocabulary, new terms like 'boat people,' 're-education camps' and 'killing fields.'"
The speech was aimed primarily at what White House officials privately describe as the "defeatocrats", the Democratic Congressmen trying to push Mr Bush into an early withdrawal.
The issue is set to come to a head next month, when the US commander in Iraq, General Petraeus, gives a progress report to Congress.
Gen Petraeus is expected to claim that the surge has produced military successes but that there has only been limited progress on the political front.
In relation to the latter, Mr Bush was today forced to backtrack after 24 hours earlier expressing frustration with the Iraqi prime minister, Nuri al-Maliki.
Alarmed by the harsh reaction of Mr Maliki, Mr Bush hurriedly rewrote his speech to praise him: "Prime Minister Maliki's a good guy, a good man with a difficult job and I support him."
The speech overall reflects the White House belief that it is shifting American public opinion behind the surge - the injection of 30,000 extra US troops into Iraq that has brought the total US force in the country to its highest-ever level, 165,000.
The Bush administration wants to keep the surge going until at least next April, at which point the overstretched military will be forced to begin reducing troop numbers anyway.
Although Gen Petraeus has not yet completed his report, a Pentagon source said the US presence could be down to 110,000 by the end of next year.
The army, as of today, had no plans o replace five brigades, each consisting of 3,400 to 4,000 soldiers, when their 15-month tours expire next summer.
Freedom's Watch, a conservative group, today launched a $15m (£7.5m) advertising campaign in 20 states saying: "It's no time to quit. It's no time for politics." The campaign will be sustained up until Gen Petraeus reports.
Mr Bush's former White House spokesman, Ari Fleischer, who works for the group, said: "We want to get the message to both Democrats and Republicans: Don't cut and run, fully fund the troops, and victory is the only objective."
The White House has been emboldened by a Gallup poll published today showing approval ratings for the Democratic-led Congress had dropped to 18%, the lowest since the survey of the public views of the legislature began in 1974, and an earlier Gallup poll showing support for the today had jumped in a month from 22% - 31%.
Two of the most influential senators on military affairs, the Democratic chairman of the armed services committee, Carl Levin, a Democrat who has been advocating an early withdrawal, and John Warner, a veteran Republican who recently broke ranks with Mr Bush over the war, issued a statement this week that lauded the surge's "tangible results".
Mr Bush, until today, has strenuously avoided making explicit references to Vietnam. It is a gamble, risking reminding Americans that Vietnam was a military quagmire and reminding them of the shambolic retreat from the embassy rooftop in Saigon.
But Mr Bush tried to turn the argument around as he made a series of contentious political parallels.
He argued that US involvement in the far east had turned it from a continent in 1939 with only two democracies - Australia and New Zealand - into one where democracy was the norm: he mentioned Japan, South Korea and Vietnam.
"In Cambodia, the Khmer Rouge began a murderous rule, in which hundreds of thousands of Cambodians died by starvation and torture and execution," Mr Bush said.
Some historians argue that it was the US covert bombing of Cambodia that produced the Khmer Rouge rather than US withdrawal from Vietnam.
Mr Bush added: "In Vietnam, former allies of the United States, and government workers and intellectuals and businessmen were sent off to prison camps, where tens of thousand perished.
"Hundreds of thousands more fled the country on rickety boats, many of them going to their graves in the South China Sea."
He said that there had been lots of critics of US involvement in Vietnam at the time - mentioning, among others, Graham Greene and a Washington Post columnist - and implying that, with the benefit of hindsight, they were wrong, just as critics of the Iraq war will later seen to be misguided.
Laugh of the Day: He is set to expand on that in a speech next week, in which he will say he has not abandoned his ambitious idea that Iraq could be in the vanguard of bringing democracy to the Middle East.
Bush's political project for Iraq now looks more fragile than ever
The bad news from Iraq continues to grow for George Bush. First, a Blackhawk goes down, taking the lives of 14 hapless soldiers and crewmen.
It is not the worst chopper disaster since the invasion, but it bumps the death toll of US personnel closer to the 4,000 mark.
Next comes the Iraqi prime minister, angrily announcing that "no one has the right to place timetables on the Iraq government. It was elected by its people."
In two sentences Bush's "benchmarks" have been tossed out of the window. These were the signs of political progress in Iraq that the White House wants to put in its report to Congress next month.
Nuri al-Maliki's outburst follows public comments from Bush expressing frustration with the Iraqi government, and hinting that it may be replaced. Maliki knew Bush was putting him under pressure to come up with a series of measures that could match the military progress which General David Petraeus will outline when he reports on the surge.
It was recently revealed that the Petraeus report will actually be drafted by the White House, using input from the general that can then be spun. But while Petraeus is a US government employee who is subject to the disciplines of command and control, Maliki isn't.
He's independent enough to show his voters that he is not going to be dictated to by foreigners, even though he is in fact their puppet, whose position would collapse if the US left Iraq.
The row symbolises the contradiction of describing a government as sovereign when its country is occupied.
Even before the latest spat between Maliki and Bush, the Iraqi prime minister was in difficulty. Half his cabinet has gone.
The main Sunni members recently resigned, following a few months after the Shia ministers loyal to the anti-occupation cleric, Moqtada al-Sadr.
This means that Maliki no longer has a guaranteed majority of supporters in parliament if it comes to a no-confidence vote.
Like Bush, Maliki has become a lame duck. Bush of course can stay in office for another 17 months.
Maliki can also stagger on in charge of a minority government, since no other Iraqi seems able or willing to put a different coalition together.
And, for all his tough talk about seeing Maliki replaced, Bush is doomed to go on supporting him. A vacuum in Baghdad would look even worse in American voters' eyes.
In one sense, the crisis only confirms what has been clear for months. Whoever sits in the Green Zone in nominal charge of Iraq's government has little power or authority beyond its walls. Bush's political project for Iraq looks more fragile than ever.