The US military said on Friday it was identifying new areas where it could work with allies to put pressure on Iran in support of President Donald Trump's new strategy, which promises a far more confrontational approach to Tehran.
Trump struck a blow against the 2015 Iran nuclear agreement on Friday in defiance of other world powers, choosing not to certify that Tehran is complying with the deal and warning he might ultimately terminate it.
He also promised to address Iran more broadly, including its support for extremist groups in the Middle East.
Major Adrian Rankine-Galloway, a Defense Department spokesman, said the Pentagon was assessing the positioning of its forces as well as planning but offered few details.
"We are identifying new areas where we will work with allies to put pressure on the Iranian regime, neutralize its destabilizing influences, and constrain its aggressive power projection, particularly its support for terrorist groups and militants," he said.
US Defense Secretary Jim Mattis said his first goal would to talk with US allies in Europe, the Middle East and elsewhere to gain a shared understanding of Iran's actions.
"Certainly we intend to dissuade them from shipping arms into places like Yemen and explosives into Bahrain and the other things they do with their surrogates, like Lebanese Hezbollah," Mattis said.
The US military has long been a strident critic of Iran, accusing it directly and indirectly of trying to undermine the United States and its allies, including in Iraq, Syria and Yemen.
The tensions escalated in recent months in Syria, where American pilots shot down two Iranian-made drones this summer.
Still, a more aggressive approach to Iran could trigger a backlash from Iran's elite Islamic Revolutionary Guard Corps (IRGC) and forces that it backs. That includes in Iraq, where US troops are fighting Islamic State and trying to keep their distance from Shiite militia aligned with Iran.