BAGHDAD - US VICE President Joe Biden said on Saturday that America's role in Iraq was switching from deep military engagement to one of diplomatic support, ahead of a complete withdrawal from the country in 2011.

He told newly sworn-in American citizens, mainly soldiers, that the United States had honoured its June 30 obligation to withdraw troops from Iraq's towns and cities and the focus was now on strengthening political ties.

'You have lost comrades, 4,322 fallen angels, over 30,000 wounded - 17,000 critical, but because of your service and their sacrifice Iraq is emerging from the terror of sectarian strife,' Mr Biden said at Camp Victory, near Baghdad. 'There is still an awful lot of hard work to do here, but thanks to you Iraqis are beginning to take responsibility for their own destiny and we will begin to welcome you home with the honour and gratitude you deserve.'

The citizenship ceremony saw 237 men and women, mainly Mexican and Filipino who joined the army while resident in the United States, as well as several Iraqis who work as military translators, take the oath of allegiance.

'Our diplomats and civilians will focus on helping Iraqis make the much needed political compromise necessary for a lasting peace and security,' Mr Biden added.

His comments came a day after meetings with Iraqi leaders in which he warned of a 'hard road ahead if Iraq is going to find lasting peace and stability.'

'It's not over yet,' Mr Biden said after talks with Prime Minister Nuri al-Maliki, which focused on bolstering trust between the conflict-torn nation's various sects. 'There are still political steps that must be taken and Iraqis must use the political process to resolve their remaining differences and advance their national interest. We stand ready if asked, and if helpful, to help in that process,' he added.

A senior US official told reporters that Mr Biden had also warned that Washington would disengage politically if violence in Iraq spiked.

'If it actually reverts to violence, then that would change the nature of our engagement. He was quite direct about that,' the official said. 'He also said if by the actions of different parties in Iraq, Iraq were to revert to sectarian violence or engage in ethnic violence, then that's not something that would make it likely that we would remain engaged.'

Kurdish authorities meanwhile announced that Mr Biden had to cancel a trip to the northern autonomous region because sandstorms prevented him from flying from Baghdad to Arbil. His trip to Iraq comes just after President Barack Obama charged him with overseeing the US departure in 2011. -- AFP