Relations between the two countries, long bound by common interests in oil and security, have strained over what some analysts see as a more assertive Saudi foreign policy.

Charges of foreign power interference in the U.S. presidential election have raised grave national security concerns and touched off multiple federal inquiries that could drag on for months.

Modern vice presidents can trace much of their political influence to the broad reforms that Jimmy Carter and Walter Mondale made to the second-highest elected office in the late 1970s.

With Iraq weakened and a civil war raging in Syria, it’s unclear whether local forces and a U.S.-led international coalition can roll back the self-proclaimed Islamic State.

U.S. and international sanctions have battered the Iranian economy and brought Tehran to negotiate over its nuclear program. Lifting them is central to a deal but will be a complex process.