Six countries reached a comprehensive agreement with Iran about the nuclear issue in Vienna. (Photo/Xinhua)

5. Iran’s nuclear issues have reached a comprehensive agreement, yet the situation still contains multiple challenges

On July 14, six countries (the U.S., Britain, France, Russia, China and Germany) reached a comprehensive agreement with Iran about the nuclear issue. The agreement, which was brokered in Vienna, came into effect on Oct. 18. Due to the poor mutual trust between Iran and the United States, there are still multiple challenges ahead in appropriately solving Iran's nuclear issues.