Iran-U.S. talks over Tehran's nuclear programme are set to kick off today in Oman, a sultanate on the eastern edge of the Arabian Peninsula.
The Americans indicate they also want to discuss Iran's ballistic missiles as well as its support of militias in the wider Middle East.
With the U.S. military buildup in the region, including carrier USS Abraham Lincoln and fighter jets, Gulf Arab nations are concerned that a possible attack on Iran may drag them in as well.
The Associated Press reporter Jon Gambrell said: "Now, these talks are really important because U.S. President Donald Trump has moved an aircraft carrier as well other warships and aircraft into the region and has threatened to militarily strike Iran if a deal can't be reached."
"But previous rounds of negotiations here in Oman, as well as in Italy, went nowhere - putting that much more pressure on these negotiations as the wider Middle East worries this could spiral into a new regional war."
Vehicles carrying Iranian Foreign Minister Abbas Araghchi were seen driving into a palace in Muscat.
Oman announced that it had mediated indirect nuclear talks between Iran and the United States with convoys for the two nations having met separately with the sultanate's top diplomat.