WASHINGTON, April 9 (UPI) -- The testimony on Iraq before the U.S. Senate Tuesday of Gen. David Petraeus and Ambassador Ryan Crocker has, at least for the moment, brought Iraq back to the top of the agenda for the feuding Democratic candidates.

But over one of the key themes raised by the testimony of the top military and civil U.S. officials in Iraq, Sens. Hillary Clinton and Barack Obama are in agreement. Each of them has said that they would not rule out "the military option" when it comes to Iran's nuclear ambitions.

Last week, Iran's President Mahmoud Ahmedinejad celebrated his country's national day of nuclear technology with the announcement that work had begun on the installation 6,000 of new centrifuges to enrich uranium at its main nuclear plant at Natanz. That is twice as many centrifuges as Iran already had functioning.

After he spoke, and while the president was inspecting Iran's improved new model of centrifuge, Iran's state-run TV stations showed schoolchildren around the country celebrating the national day by parading to martial music and chanting "nuclear power is our natural right."

But Iran's nuclear ambitions are not to the only way that Tehran is likely to feature more prominently in this year's U.S. presidential election campaign. Petraeus and Cricker both warned in their Senate testimony that Iran is a major part of their problem in Iraq.