In a prelude to a possible second round of peace talks in Pakistan, Iran ramped up its rhetoric against the United States on Saturday, warning of retaliation if the US kept up its shipping blockade.

Iran’s Khatam al-Anbiya Central Headquarters, the operational centre of the Islamic Republic’s armed forces, warned of a “severe reaction” if the US continued its “naval blockade, maritime piracy and robbery in the region”.

Iran’s defence ministry also said that much of the country’s missile strength...