British troops have achieved many tangible successes in Iraq - securing oil platforms, rounding up rogue police units and driving smugglers carrying weapons and contraband from waterways and border crossings. But now these missions will be relegated to the Iraqi army. Under proposals laid out by Prime Minister Tony Blair on Wednesday, Britain will withdraw about 1,600 troops from Iraq over the coming months and hopes to make other cuts to its 7,100-strong contingent by late summer. British troops would likely stay in the southern Basra region until at least 2008, training local forces, working to secure the Iran-Iraq border and maintaining supply routes to US and coalition troops in central Iraq, Blair told legislators. Britain could further reduce its force level to below 5,000 once a base at Basra Palace is transferred to Iraqi control in late summer, the prime minister said.