Iran's national security policy is the product of many, and sometimes competing, factors: the ideology of Iran's Islamic revolution; Iranian leadership's perception of threats to the regime and to the country; long-standing Iranian national interests; and the interaction of the Iranian regime's various factions and constituencies. Some experts assert that the goal of Iran's national security strategy is to overturn a power structure in the Middle East that Iran asserts favors the United States and its allies Israel, Saudi Arabia, and other Sunni Muslim Arab regimes. Iran characterizes its support for Shiite and other Islamist movements as support for the "oppressed" and asserts that Saudi Arabia, in particular, is instigating sectarian tensions and trying to exclude Iran from regional affairs. Others interpret Iran as primarily attempting to protect itself from U.S. or other efforts to invade or intimidate it or to change its regime. Its strategy might, alternatively or additionally, represent an attempt to enhance Iran's international prestige or restore a sense of "greatness" reminiscent of the ancient Persian empires. From 2010 until 2016, Iran's foreign policy also focused on attempting to mitigate the effects of international sanctions on Iran. Iran employs a number of different tools in pursuing its national security policy. Some Iranian policy tools are common to most countries: traditional diplomacy and the public promotion of Iran's values and interests. Iran also has financially supported regional politicians and leaders. Other tools Tehran uses pose significant challenges to U.S. policy: Iran provides direct material support to armed groups, some of which use terrorism to intimidate or retaliate against Israel or other regional opponents of Iran. Iran's armed support to Shiite-dominated allied governments, such as those of Syria and Iraq, has aggravated challenges from Sunni insurgent groups by fueling Sunni popular resentment. Iran's national security policy (like the U.S. effort to counter Iran strategically) overwhelmingly focuses on the Near East region, including on U.S. operations, allies, and activities in that region. It is that region where all the various components of Iran's foreign policy interact. Iran's foreign policy also seems to be directed at influencing the policies and actions of big powers, such as those in Europe as well as Russia, that are active in the Near East-either as partners or antagonists of U.S. interests in that region. Some experts forecast that Iran's foreign and defense policies might shift after international sanctions were eased in January 2016 in accordance with the July 2015 multilateral nuclear agreement with Iran (Joint Comprehensive Plan of Action, JCPOA). Some asserted that the additional financial resources would cause Iran to try to expand its regional influence further. Others assessed that the nuclear agreement would cause Iran to moderate its regional behavior in order not to jeopardize the agreement and its benefits. U.S. officials and U.S. reports assert that there has been no observable alteration of Iran's pursuit of its core regional activities, particularly to materially support friendly governments and pro-Iranian factions. However, Iran is using the nuclear agreement to ease its international diplomatic isolation and to try to develop itself as a regional energy and trade hub while at the same time exploring new weapons buys. Supreme Leader Ali Khamene'i and key hardline institutions, such as the Islamic Revolutionary Guard Corps (IRGC), appear to have blocked any compromises of Iran's core goals, while at the same time allowing Iran to re-integrate into regional and international diplomacy.