The kingdom of Saudi Arabia's relations with the United States, its stability, and its future trajectory are subjects of continuing congressional interest. In particular, Saudi leadership transitions, trends in global oil prices, Saudi budget pressures and reform plans, aggressive transnational terrorist threats, assertive Saudi foreign policies, and Saudi-Iranian tensions have fueled recent congressional discussions. U.S.-Saudi security cooperation and U.S. concern for the continuing global availability of Saudi energy supplies continue to anchor official bilateral relations as they have for decades. In this context, the Trump Administration's efforts to reinvigorate U.S.-Saudi relations have drawn increased public attention and have generated debate. Previously, the Obama Administration had differed with Saudi leaders over Iran, the Iranian nuclear program, and conflicts in Syria, Iraq, and Yemen. Amid some continuing differences on these issues, bilateral ties have been defined since 2017 by arms sale proposals, Yemen-related security cooperation, and shared concerns about Iran, Al Qaeda, and the Islamic State organization (IS, aka ISIL/ISIS or the Arabic acronym Da'esh ). From 2012 through 2016, the Obama Administration notified Congress of proposed Foreign Military Sales to Saudi Arabia with a potential value of more than $45 billion. President Donald Trump and Saudi officials announced agreement on some of these sales and others during the President's May 2017 trip to the kingdom, as part of a package that may potentially be worth more than $110 billion. This package of previously discussed and newly proposed defense sales is intended to address Saudi needs for maritime and coastal security improvements, air force training and support, cybersecurity and communications upgrades, missile and air defenses, and enhanced border security and counterterrorism capabilities (see " Arms Sales, Security Assistance, and Training " below and Appendix B ). King Salman bin Abd al Aziz Al Saud (age 82) succeeded his late half-brother King Abdullah bin Abd al Aziz following the latter's death in January 2015. King Salman later announced dramatic changes to succession arrangements left in place by King Abdullah, surprising observers of the kingdom's politics. King Salman first replaced his half-brother Crown Prince Muqrin bin Abd al Aziz with their nephew, Prince Mohammed bin Nayef bin Abd al Aziz, who was then Interior Minister and counterterrorism chief. The king then named his own son, Prince Mohammed bin Salman bin Abd al Aziz, then 29, as Deputy Crown Prince and Defense Minister. In June 2017, Prince Mohammed bin Nayef was relieved of his positions and Prince Mohammed bin Salman (age 33) was elevated further to the position of Crown Prince, placing him in line to succeed his father (see Figure 1 , Figure 2 , and " Leadership and Succession " below). Both princes are members of the generation of grandsons of the kingdom's late founder, King Abd al Aziz bin Abd al Rahman Al Saud (aka Ibn Saud). The succession changes and Crown Prince Mohammad bin Salman's efforts to assert his role as the shaper of the kingdom's national security and economic policies have resulted in an apparent consolidation of authority under one individual and sub-branch of the family that is unprecedented in the kingdom since its founding. Shifts in Saudi foreign policy toward a more assertive posture—typified by the kingdom's military operations in neighboring Yemen and a series of regional moves intended to counteract Iranian initiatives—have accompanied the post-2015 leadership changes. Saudi leaders launched military operations in Yemen following the early 2015 ouster of Yemen's transitional government by the Zaydi Shia Ansar Allah (aka Houthi) movement and backers of the late former Yemeni President Ali Abdullah Saleh (see " Conflict in Yemen " below). A U.S.-facilitated, Saudi-led coalition air campaign has conducted strikes across the country since late March 2015, coupled with a joint Saudi and Emirati ground campaign aimed at reversing Houthi gains and compelling them to negotiate with U.N.-recognized transition leaders. Concerns about Yemeni civilian deaths in Saudi airstrikes, the operation's contribution to grave humanitarian conditions, and gains by Al Qaeda and Islamic State supporters have led some Members of Congress and U.S. officials to urge all parties to seek a prompt settlement. President Obama maintained U.S. logistical support for Saudi operations in Yemen but decided in 2016 to reduce U.S. personnel support and limit certain U.S. arms transfers. President Trump has chosen to proceed with precision guided munition technology sales that the Obama Administration deferred. In September 2018, the Trump Administration certified conditions set by Congress on Saudi actions in Yemen and renewed calls for a political solution. A U.S. State Department travel advisory issued in April 2018 warns that "rebel groups operating in Yemen have fired long-range missiles into Saudi Arabia, specifically targeting populated areas and civilian infrastructure" and that "rebel forces in Yemen fire artillery at Saudi border towns and launch cross-border attacks against Saudi military personnel." U.S. support to the kingdom's operations in Yemen and Saudi use of U.S.-origin weaponry has drawn new attention to congressionally reviewed arms sales and questions of authorization. In the 114 th Congress, some Members scrutinized proposed sales of thousands of guided air-to-ground munitions and tanks to Saudi Arabia in the context of concerns about the Saudi military's conduct in Yemen (see Appendix D below). In the 115 th Congress, legislation has been enacted that prohibits the obligation or expenditure of U.S. funds for in-flight refueling operations of Saudi and Saudi-led coalition aircraft that are not conducting select types of operations if certain certifications cannot be made and maintained (Section 1290 of the FY2019 National Defense Authorization Act, P.L. 115-232 , Appendix D ). The provision is subject to an Administration national security waiver. A similar measure would place conditions on the transfer of any air-to-ground munitions to Saudi Arabia ( S.J.Res. 40 ), and, in June 2017, the Senate narrowly voted to reject a motion to further consider a joint resolution of disapproval ( S.J.Res. 42 ) on proposed sales of precision guided munitions to the kingdom. The House and Senate also have considered resolutions ( H.Con.Res. 81 and S.J.Res. 54 ) that would direct the President to end U.S. military support for Saudi operations in Yemen unless Congress specifically authorizes the continuation of such support. Inside the kingdom, arrests of Islamic State (IS) supporters have continued since 2014, as Islamic State affiliates have claimed responsibility for a series of deadly attacks against Saudi security forces and members of the kingdom's Shia minority across the country (see " The Islamic State's Campaign against the Kingdom " below). Saudi authorities report having disrupted planned IS attacks on government targets in 2017 and counted 34 terrorist attacks in 2016, including an attempted IS-claimed suicide bombing against the U.S. Consulate General in Jeddah. Saudi leaders and their IS adversaries have reiterated their hostility toward each other since 2015, with Saudi leaders proposing new transnational counterterrorism cooperation and IS leaders redeclaring war against the royal family, condemning official Saudi clerics, and urging attacks inside the kingdom (see " Terrorism Threats and Bilateral Cooperation "). The current U.S. State Department travel advisory for Saudi Arabia warns that "terrorist groups continue plotting possible attacks" and that "terrorists may attack with little or no warning." Since 2011, significant shifts in the political and economic landscape of the Middle East have focused international attention on Saudi domestic policy issues and reinvigorated social and political debates among Saudis (see " Domestic Issues " below). These regional shifts, coupled with ongoing economic, social, and political changes in the kingdom, may make sensitive issues such as political reform, unemployment, education, human rights, corruption, religious freedom, and extremism more prominent in U.S.-Saudi relations than in the past. U.S. policy initiatives have long sought to help Saudi leaders address economic and security challenges in ways consistent with U.S. interests. Recent joint U.S.-Saudi diplomatic efforts to strengthen economic, educational, and interpersonal ties have focused on improving opportunities for the kingdom's young population. Tens of thousands of Saudi students continue to pursue higher education in the United States, although numbers have declined in response to Saudi government funding changes. Some nongovernment observers have called for a reassessment of U.S.-Saudi relations amid the kingdom's ongoing military campaign in Yemen. They cite concern about human rights conditions in the kingdom, as well as resurgent questions about the relationship between religious proselytization by some Saudis and the appeal of violent Islamist extremism. U.S. officials have called publicly for the kingdom to seek a negotiated settlement in Yemen, allow peaceful expressions of dissent at home, and help fight extremism abroad. Any more strident official U.S. criticisms of the kingdom's policies traditionally remain subjects of private diplomatic engagement rather than official public discussion. Saudi concerns about U.S. leadership and policies in the Middle East grew during the Administrations of Presidents George W. Bush and Barack Obama, in parallel to U.S. concerns about Saudi priorities and choices. In particular, Saudi leaders at times signaled their displeasure with U.S. policy approaches to Egypt, Israel and the Palestinians, Bahrain, Iraq, Syria, and Iran. Saudi officials also opposed the changes to U.S. sovereign immunity law that were made by the 114 th Congress through the Justice Against Sponsors of Terrorism Act ( S. 2040 , P.L. 114-222 , aka JASTA) and have sought their amendment or repeal.