U.S. Defense Secretary Robert Gates

U.S. Defense Secretary Robert Gates says the United States is looking to a long-term military presence in Iraq similar to its arrangement with South Korea.

Gates says the presence would be based on a mutual agreement with Iraq. He says the agreement would protect the sovereignty of Iraq's government and limit what U.S. forces can do while in the country.

In addition to South Korea, Gates referred to Japan as another model for a long-term U.S. military presence.

Earlier Thursday, the U.S. ground forces commander in Iraq said he may need more time to assess the impact of the U.S. troop surge in the country, beyond the September assessment President Bush and Congress are expecting.

Lieutenant General Ray Odierno said the last of the additional U.S. combat troops will not be in place until mid-June. He said they will need considerable time after that to make a major impact.

The general also said the U.S. military is increasing efforts to reach out to insurgent groups to get them to stop their attacks.

In violence Thursday, Iraqi authorities said a suicide bomber killed at least 20 people at a police recruiting center in the western city of Fallujah. The U.S. military put the casualty toll at one dead, an Iraqi policeman, and eight wounded.