The US has begun cracking down on Iranian-backed forces operating in Iraq and is monitoring the Iran-Iraq border to stop further infiltration, the New York Times reported on 30 April. A group of fighters from the Badr Brigade, the military wing of the Tehran-based Supreme Council for Islamic Revolution in Iraq (Sciri), were detained by US forces on 29 April as they moved south. Washington has repeatedly warned Tehran not to interfere in the post-war Iraqi political settlement, fearing the emergence of a pro-Iranian Shiite regime. 'We are going to increase our focus on routes from Iran,' said US Major-General William Webster. 'As the country becomes more stable, we can structure ourselves to shift to the east.' US officials, according to the New York Times, have received intelligence reports of Iranian agents and Iraqi Shiites moving into southern towns to recruit supporters and organise demonstrations. Some of the Badr fighters who have moved into Iraq since the war to topple Saddam Hussein are said to be Revolutionary Guard members. The US has broadcast radio messages aimed at Iraqis in Iran, warning them to leave any weapons behind if they choose to return.