World Notes THE GULF

United Nations Secretary-General Javier Perez de Cuellar arrived in Tehran on the first leg of a difficult mission: to negotiate a cease-fire in the seven- year war between Iran and Iraq. The two sides had been expected to stop fighting at least until the Secretary-General's visit ends this week. But after only a three-day lull, Iraqi warplanes attacked Iranian cities and industrial sites in what Iraqi President Saddam Hussein called a "day of revenge" for Iranian missile attacks on Kuwaiti targets the week before. Iran, meanwhile, said it could not "take the risk" of observing an unconditional cease-fire, as called for by a U.N. Security Council resolution two months ago. If Perez de Cuellar's mission fails, the next step will be a U.S. campaign for an international arms embargo against Iran.