EL AVIV — American and Israeli intelligence officials have concluded that Yasir Arafat has forged a new alliance with Iran that involves Iranian shipments of heavy weapons and millions of dollars to Palestinian groups that are waging guerrilla war against Israel.The partnership, officials said, was arranged in a clandestine meeting in Moscow last May between two top aides to Mr. Arafat and Iranian government officials. The meeting took place while Mr. Arafat was visiting President Vladimir V. Putin of Russia, according to senior Israeli security officials who declined to describe the precise nature of their information.The new alignment is significant...