U.S. Defense Secretary Ash Carter has arrived in Baghdad on an unannounced visit to consult with Iraqi leaders and meet with U.S. military commanders.

It is Carter's first visit to Iraq since taking over at the Pentagon in February.

He is expected to focus on progress toward political reconciliation between the Shiites, who control the central government, and the minority Sunnis and Kurds, who feel largely disenfranchised and do not trust the government. It is this split that's at the heart of Iraq's inability to expel the Islamic State, which controls large swaths of the country.

Carter also is expected to get updates on U.S. efforts to train and equip Iraqi security forces, who are gearing up for a counteroffensive in Ramadi, the capital of Sunni-dominated Anbar province.

There are about 3,360 U.S. troops in Iraq.