The United States has no plans to consult Iran on any potential military action in Iraq, the Pentagon said Monday, but left the door open to diplomatic discussions on the crisis.
Pentagon spokesman Rear Admiral John Kirby said "there is absolutely no intention, no plan to coordinate military activities between the United States and Iran."
US and Iranian diplomats might, however, address the situation in Iraq on the margins of negotiations on Tehran's nuclear program, which will take place this week in Vienna, Kirby told reporters.
"It's possible on the sideline of those discussions, there could be discussions surrounding the situation in Iraq," he said.
"It's not without precedent that we speak about security issues with Iran. There were discussions about Afghanistan with Iran in the not too distant past," said Kirby, an apparent reference to talks with Tehran prior to the US-led invasion of Afghanistan in 2001.
But he added: "There are no plans to consult Iran about military activities inside Iraq."
Kirby said the United States has encouraged Iran and other neighboring countries to "play a constructive role" and respect Iraq's "territorial sovereignty."
The Pentagon's comments came after Secretary of State John Kerry triggered speculation about potential US-Iran military cooperation in an interview with Yahoo News.
"I wouldn't rule out anything that would be constructive," Kerry said when asked if the United States would cooperate militarily with its traditional foe Iran.
Kerry said time would tell what Iran would be ready to do on behalf of its allies in the Shia-led government in Baghdad.
"Let's see what Iran might or might not be willing to do before we start making any pronouncements," Kerry said.
The lightning advance of extremists from the Islamic State of Iraq and the Levant (ISIL) across Iraq, including the capture of Mosul, has alarmed both Tehran and Washington.
Both governments, for their own reasons, oppose the rise of the Sunni jihadists and have a common interest in seeing the Baghdad government fend off the onslaught.
ISIL's offensive has raised fears of a new sectarian civil war between Sunnis and Shias in the country from which US forces withdrew in December 2011.