Robert Gates

U.S. Defense Secretary Robert Gates says the Bush administration "probably underestimated" the difficulty of achieving national political reconciliation in Iraq.

Speaking to reporters on his return from a four-day trip to the Middle East Thursday, Gates called Iraqi political developments "somewhat discouraging," but added he hopes for improvement.

Gates noted the difficulties encountered in trying to get Iraqi politicians to agree on important legislation regulating the country's oil industry, or on a timetable for provincial elections.

This week the largest Sunni Arab bloc withdrew its six ministers from Prime Minister Nouri al-Maliki's cabinet, worsening sectarian political divisions.

Despite these problems, Gates says, the security situation in Iraq is "more encouraging" than he would have expected three or four months ago.

The U.S. defense chief says coalition forces' successful efforts in al-Anbar province to partner with Sunni tribal leaders against al-Qaida are now being copied elsewhere in the country.

Some information for this report was provided by AP.