Engineering firms working with Iran’s Revolutionary Guard, certain individuals and shipping companies have been slapped with punitive sanctions by the US Department of the Treasury. The new measures, which were announced in Washington on Wednesday, constitute the latest round of measures aimed at forcing Tehran to end its nuclear development program. Government officials said the Revolutionary Guard remains the principle focus of sanctions because of its control over Iran’s economy in the areas of defense production including missile and nuclear programs; oil and gas; and its links to terrorism. Firms violating the sanctions stand to lose the ability to transact business in the United States.