Iranian forces have battled for years in the lonely canyons and deserts on the Afghan border against opium and heroin traffickers, winning rare praise from the United States and aid from Europe for the fight along one of the world's busiest drug routes. But now, Western nations have told Iran that they could cut off any new help to Iran's anti-drug units unless the Islamic regime halts uranium enrichment, which Washington and its allies worry could be used to develop nuclear arms. The warning was a small but potentially significant item tucked amid an array of trade and economic incentives seeking to sway Iranian leaders to strike a deal. Iran has not formally responded to the package, presented June 14 by the five permanent United Nations Security Council members plus Germany. Roberto Arbitrio, head of the UN drugs and crime office in Iran, said the war on drugs should be viewed as "a non-political area of mutual interest."