World powers will not be able to negotiate a better deal with Iran than the landmark 2015 nuclear deal, Iran’s Foreign Minister Mohammad Javad Zarif tweeted on Monday. Iran threatened on Monday to restart deactivated centrifuges and ramp up its enrichment of uranium to 20 percent purity...

Oil prices firmed on Monday on tensions over Iran’s nuclear program but gains were capped by concerns about global economic growth and consequently oil demand. Brent crude futures rose 38 cents, or 0.6%, to $64.61 a barrel by 1:04 p.m. EDT. U.S. West Texas Intermediate (WTI) crude futures...

 A 5.7-magnitude earthquake struck southwest Iran near the border with Iraq Monday, the country's national seismological center reported. The quake, whose epicenter was in the Masjed Soleiman area of Khuzestan province, hit at 11:30 a.m. (0700 GMT) at a depth of 17 kilometers....

Britain’s seizing of an Iranian oil tanker last week was a threatening act that will not be tolerated, Iran’s Defence Minister Amir Hatami said on Monday in a speech broadcast live on state television. Royal Marines impounded the tanker in Gibraltar on Thursday on suspicion it was...