(CNN)King Salman of Saudi Arabia has inherited the throne from his older brother and with it a host of pressing challenges in a turbulent region. To the south, Yemen is in chaos. To the north, the militant group ISIS is wreaking havoc in Iraq and Syria. More broadly, Saudi Arabia remains locked in a regional cold war with Iran. Within the kingdom's borders, Salman has to decide how to pace sensitive reforms while keeping a lid on extremism. The stakes are high in one of the leading regional powers in the Middle East and a key U.S. ally. "Saudi Arabia has been critical to preserving some degree of regional stability in the face of a growing Iranian threat, during the rise of Islamic extremism that followed the U.S. invasions of Afghanistan and Iraq, and during the new wave of upheavals that began in the spring of 2011," Anthony H. Cordesman, a Middle East expert at the Center for Strategic and International Studies, wrote in a commentary this month.
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Yemen's pro-Saudi government has crumbled amid sectarian unrest
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Saudi Arabia also faces difficulties in its cold war with Iran and the fight against ISIS
Here are some of the main challenges @placeholder now faces: