BAGHDAD: The top American general in Iraq says al-Qaida and other insurgent groups might seek to strengthen their operations after American forces leave at the end of the year.

However, Gen. Lloyd Austin also told reporters Monday he did not expect the security situation to completely disintegrate.

Warning of another challenge, Austin said Shiite militia groups that have mainly attacked American forces will pose a threat to the Iraqi government even after American troops are gone.

All American forces must be out of Iraq by the end of this year. Austin said there are just under 20,000 troops and eight American bases left in the country.