Delegations from the United States and Iran on Saturday resumed "indirect" negotiations on a nuclear deal in Rome, with another round of talks set for next Saturday, after experts hash out technical matters Wednesday.

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.

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.