Al-Qaida's network in Iraq has never been closer to defeat, said the US ambassador to that country Saturday. He also praised Prime Minister Nouri al-Maliki for his moves to rein in Shiite and Sunni militant groups. Ryan Crocker's comments came as Iraqi forces have been conducting crackdowns on al-Qaida militants in the northern city of Mosul and on Shiite militiamen in the southern city of Basra. Thousands of Iraqi forces last week also moved into the Shi'ite militia stronghold of Sadr City in Baghdad to impose control for the first time in years. But truces with the powerful Mahdi Army militia that have calmed violence in Basra and paved the way for the Sadr City deployment have been strained in the past two days. Supporters of anti-US cleric Muqtada al-Sadr, who heads the Mahdi Army, accused Maliki on Saturday of seeking to eliminate their movement and warned that "dark clouds" hang over the truce.