U.S. Vice President Dick Cheney, an architect of the U.S-led invasion of Iraq, made an unannounced visit to Baghdad on Monday, just days before the fifth anniversary of the war.

Cheney, who last visited Baghdad in May, made Iraq the first stop of his nine-day Middle East tour that will also take him to Saudi Arabia, Jerusalem, the Palestinian territories, Turkey and Oman.

He arrived amid an upsurge in violence since January, including a number of suicide bombings that the U.S. military has blamed on al Qaeda.

But military commanders say this does not represent a trend and that attacks are actually down 60 percent from the middle of last year.

Cheney, a strong supporter of sending an additional 30,000 U.S. troops to Iraq last year, has warned critics that a premature U.S. withdrawal would spark chaos and further bloodshed.

Both Democratic presidential candidates, Hillary Clinton and Barack Obama, have vowed to start bringing troops home in 2009 if elected.

Republican candidate John McCain, also in Baghdad, said last week the quickest way of bringing the war to a conclusion was by "continuing the surge".

U.S. President George W. Bush will receive a new assessment soon from the top U.S. commander in Iraq, General David Petraeus, and U.S. Ambassador Ryan Crocker that he will consider in deciding whether any changes are needed to U.S. strategy.

The United States wants Saudi Arabia and other Arab allies like Egypt to establish diplomatic presences in Iraq.