That the talks are even happening represents a historic moment, given the decades of enmity between the two countries since the 1979 Islamic Revolution and the U.S. Embassy hostage crisis.

US and Iranian delegations will gather in Rome Saturday for a second round of high-level talks on Tehran’s nuclear program amid tempered optimism about a diplomatic way forward.

Iran and the U.S. are trying to resolve their decades-long standoff over Tehran's atomic aims under the shadow of Trump's threat to unleash military action if diplomacy fails.