Note: Today is the third in a series of posts that detail Eurasia Group's Top Risks for 2013.

The Middle East will enter a new phase in 2013. Arab Spring will give way to Arab Summer, as the region faces a series of increasingly complicated overlapping conflicts. As Americans and Europeans resist deeper involvement, rivalries among Saudi Arabia, Iran, and Turkey, competition for influence between Sunni and Shia, a lack of economic progress, and a resurgence of militant groups will each heighten tensions.

Syria remains the central arena of conflict, as Shia powers -- Iran and Lebanese Hezbollah -- on the one side, and Sunni states -- Turkey, Saudi Arabia and Qatar -- on the other compete for leverage. Jihadists have also entered the fray, and turmoil has spilled across the country's borders into Lebanon, Turkey, Jordan, and Iraq.

Emerging conflicts elsewhere are less obvious. Egypt, Tunisia, and Morocco now have moderate Islamist governments. In Jordan and Kuwait, Islamist opposition groups threaten the governing dominance of secular administrations. But while the words and actions of mainstream parties like Egypt's Muslim Brotherhood and Tunisia's Ennahda make headlines in the West, the more serious risk comes from militant organizations that threaten the ability of new leaders to govern and maintain security.

Fueling this trend is the reality that, across the region, new leaders are trying to consolidate power and build popularity at a time when complicated economic problems demand solutions that will make large numbers of people angry. New governments in Tunisia, Libya, Egypt, and Yemen will last only if they can deliver tangible economic progress for an increasingly frustrated and impatient public.

The risk that a Salafist or jihadist group can exploit these frustrations to seize power in 2013 is low, but groups like al Qaeda in the Islamic Maghreb, al Qaeda in the Arabian Peninsula, al-Shabab, and smaller affiliates continue to attract support and new followers by using resentments against local regimes to foster anger at America and the West. 

But Iraq may become 2013's newest hotspot. Sunni-Shia tensions are growing, and none of Syria's neighbors is more vulnerable to the threats created inside that country by radical Wahhabi clerics, often with Saudi or Qatari support, now fueling the emergence of an increasingly radicalized and militarily experienced Salafist movement. The Kurdish regional government is becoming more aggressive in promoting its energy development agenda at Baghdad's expense, and Sunni-led violence inside the country might well encourage Iraq's Shia-led government to forge closer ties with Tehran, antagonizing the governments of Saudi Arabia and Turkey.

The Obama administration wants to focus on domestic challenges and an ongoing foreign policy shift toward Asia. But regional rivalries are heating up, and Americans and Europeans will only add to the uncertainty by keeping their distance -- in hopes that they don't get burned. 

On Wednesday, we'll profile Risk #4: Washington Politics.