The study by the Senate Foreign Relations Committee examined the U.S. relationship with the six nations of the Gulf Cooperation Council - Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates and Oman - against a fast-moving backdrop. In just the last two days, Saudi Arabia's ruler named Defense Minister Prince Salman bin Abdul-Aziz as the country's new crown prince after last week's death of Prince Nayef, and Kuwait's government suspended parliament for a month over an internal political feud.

The latest developments inject even more uncertainty as the Middle East deals with the demands of the Arab Spring, the end to U.S. combat operations in Iraq at the end of 2011 and fears of Iran's nuclear program.

"Home to more than half of the world's oil reserves and over a third of its natural gas, the stability of the Persian Gulf is critical to the global economy," the report said. "However, the region faces a myriad of political and security challenges, from the Iranian nuclear program to the threat of terrorism to the political crisis in Bahrain."