Sen. John McCain arrived in Baghdad Sunday for an unexpected visit as the war-ravaged country observed five years of US invasion. The visit by one of the foremost supporters of the 2003 invasion and soon-to-be Republican presidential nominee came as Kurds in northern Iraq commemorated the 20th anniversary Sunday of a horrific chemical weapons attack that killed an estimated 5,600 people. Five years after US-led invasion troops swept through Iraq, feared dictator Saddam Hussein is dead and an elected government sits in Baghdad – but Iraqis remain beset by rampant violence, political stalemate, economic woes and the humiliation of a foreign occupation. Although the level of violence has dropped over the past few months, the top US commander in Iraq, General David Petraeus, says the US and Iraqi governments both recognize the nation's leaders have not made sufficient progress in settling their political differences. Independent website Iraqbodycount.org estimates the number of civilian deaths at up to 90,000 although other figures, including Iraqi government and UN statistics, are much higher. Despite their rapid victory in 2003, US soldiers today are routinely targeted by rockets, roadside bombs, and suicide attacks, mired in a war against Al-Qaeda fighters, especially in northern Iraq. The war in Iraq has already cost the United States more than $400 billion by the most conservative tally, but the total bill could surpass three trillion dollars, according to Nobel Prize-winning economist Joseph Stiglitz. By the Pentagon's count, $527 billion were allocated from Sept. 2001 through Dec. 2007 to finance the war against terrorism, including $406 billion for Iraq. __