"Iran employs a number of different national security policy tools, including traditional diplomacy and the public promotion of Iran's values and interests. Of greater concern to U.S. officials is that Iran advances its interests by providing material support to armed groups, some of which conduct acts of international terrorism. Iran's armed support to Shiite-dominated allied governments, such as those of Syria and Iraq, has fueled Sunni popular resentment. Iran also has financially supported regional politicians and leaders. Iran has used the July 2015 multilateral nuclear agreement with Iran (Joint Comprehensive Plan of Action, JCPOA) to ease its international diplomatic isolation and to try to develop itself as a regional energy and trade hub and to explore new weapons buys. [...] Iran's national security policy focuses most intently on the Near East region, including on U.S. operations, allies, and activities in that region. Iran's policy also seems to be directed at influencing the policies and actions of big powers, such as those in Europe as well as Russia, as partners of Iran and/or antagonists of U.S. actions in the region. [...] The Trump Administration has cited Iran's regional 'malign activities' and repeated ballistic missile tests to assert that Iran 'is now feeling emboldened' and that 'Iran's provocative actions threaten the United States, the [Middle East] region, and the world.' The Administration has begun a comprehensive policy review, sanctioned additional Iran missile entities under existing authorities, and sought to forge a regional coalition to counter Iran."
CRS Report for Congress, R44017
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html