Factbox: U.S. imposes new sanctions on Iran after U.N. standoff over arms

FILE PHOTO: A staff member removes the Iranian flag from the stage after a group picture with foreign ministers and representatives of the U.S., Iran, China, Russia, Britain, Germany, France and the European Union during the Iran nuclear talks at the Vienna International Center in Vienna, Austria July 14, 2015. REUTERS/Carlos Barria

WASHINGTON (Reuters) - The United States on Monday imposed new sanctions on individuals and entities involved in Iran's nuclear, missile and conventional arms programs, to support its assertion that all U.N. sanctions against Tehran are now resumed.

The impetus behind the U.S. action is the impending expiry of a U.N. arms embargo on Iran and a desire to warn foreign actors - U.S. entities are already barred from such trade - that if they buy or sell arms to Iran they will face U.S. sanctions.