The two former advisers said they both think both the United States and Iran are divided on how to proceed regarding Tehran's nuclear aspirations, making progress harder to achieve before the next U.S. president takes office, The Washington Post reported Wednesday.

U.S. President George Bush has said all options are on the table.

"Don't talk about 'do we bomb them now or later?' " said Brent Scowcroft, national security adviser to presidents Gerald Ford and George H.W. Bush, during a discussion at the Center for Strategic and International Studies on U.S.-Iran negotiations.

Zbigniew Brzezinski, President Jimmy Carter's national security adviser, said the Bush administration's policy of maintaining a military option was "counterproductive."

"I don't want the public to believe a preemptive attack can be justified," Brzezinski said.

Brzezinski and Scowcroft did say Undersecretary of State William Burns's participation at the most recent negotiations with Iran was a positive step.

"It brings the U.S. solidly in with the Europeans and the Russians," Scowcroft said.