DUBAI, United Arab Emirates -- Iran and the United States held a fourth round of negotiations Sunday over Tehran’s rapidly advancing nuclear program, just ahead of a visit by President Donald Trump to the Middle East this week.

Iranian Foreign Minister Abbas Araghchi arrived in Muscat to attend the fourth round of "indirect" talks between Iran and the United States over Tehran's nuclear program, according to the official Islamic Republic News Agency.

Suspected Islamist militants attacked a Nigerian army base and captured soldiers and ammunition during a raid in the insurgency-hit northeastern Borno state in the early hours of Monday, two security sources told Reuters.