Explosions over Baghdad last night were fireworks, celebrating what’s being called "National Sovereignty Day’ as Iraq forces are taking over the security of several major Iraqi cities and U.S. forces begin to pull out. Iowa Senator Chuck Grassley says the change-over has him cautious about the situation, for fear of renewed violence.

Grassley says, "I have a little bit of concern, but less concern now because it seems like we’ve, in the last three years, had a pretty structured approach to training their troops." Four American soldiers were killed in Iraq in the past day. Grassley says the U.S. occupation of Iraq has been made more difficult by the fact we don’t have the international support like during the Persian Gulf War nearly two decades ago.

Grassley says, "When you don’t have the cooperation of a lot of other people, like we have with Japan and South Korean and all of Europe since World War Two and the Korean War, without having massive support like that, there’s a limited period of time that we can police another country."

The hand-over of security today comes as part of a U.S.-Iraqi pact. Grassley says he hopes we’ve helped to bring a better and more prosperous future to the nation of Iraq.

"Our goal is to stabilize it and hopefully we’ve done that, but you really won’t know for a while," Grassley says, "I’m glad that this is happening. A little nervous, but not too nervous." Thousands of people attended outdoor rallies overnight and sang patriotic songs.

Iraqi leaders who spoke at the celebrations said the day of "sovereignty" could not have happened without America’s help. The 2003 invasion led to the capture and ousting of former Iraqi dictator Saddam Hussein, who was tried, convicted and put to death in 2006.