Mullen's warning of the perils arising from the two sides' inability to communicate and understand each other's intentions — "Even in the darkest days of the Cold War, we had links to the Soviet Union" — seems especially prescient amid the fallout from the alleged plot to kill the Saudi ambassador to Washington, blamed by the U.S. on "elements of the Iranian government." Claims that officials within the elite Quds Force of the Iranian Revolutionary Guards Corps initiated a bizarre scheme via an Iranian-American used-car salesman — described by his former business partner as "a sort of hustler" — to enlist the services of a Mexican drug gang for a terrorism strike in the U.S. capital have been seized on by the Administration to press for tougher international action against Tehran.

"We see this as a chance to go out to capitals and around the world and talk to allies and partners about what the Iranians tried to do," an unnamed official told the Washington Post. "We're going to use this to isolate them to the maximum extent possible." Vice President Joe Biden added, darkly, that when it came to responding to Iran's behavior, "nothing has been taken off the table."

U.S. officials fanned out on Wednesday to enlist the support of foreign governments for further sanctions. (The U.S. has banned Iran's airline from operating in the U.S. and has frozen its assets.) And the Administration plans to approach the U.N. Security Council, seeking action to "hold Iran accountable" over the plot. While Britain and France have signaled support, it's difficult to imagine that the revelations will persuade countries skeptical of the U.S.'s Iran policy to change their positions. As National Iranian American Council President Trita Parsi tells TIME, "They have to be sure the evidence of involvement by the government of Iran is very solid, because they can't afford another Colin Powell moment at the Security Council." (The former Secretary of State briefed the council in February 2003 on U.S. claims about Iraq's weapons programs, on which it justified its invasion, but the claims later proved to be unfounded.) "And the evidentiary bar is going to be set pretty high at the Security Council precisely because of the Colin Powell experience," Parsi adds.