• Sunni-Shiite tensions. Overshadowing for the first time Lebanon's traditional Christian-Muslim divide, is the broader schism among Muslims in the Middle East.
THE CRUX: The main conflict between the West and Iran is its nuclear-energy program, which the US has criticized as a cover for developing weapons. Washington has also accused Tehran of backing Hizbullah in Lebanon and destabilizing Iraq. There are also tensions between an increasingly powerful Shiite Iran and the Sunni Persian Gulf states.
THE STATUS: The US released a new National Intelligence Estimate in December concluding that Iran halted a weapons program in 2003 – reversing previous assessments and lowering expectations for an air strike. Iran's relations with Sunni Arab neighbors have also improved, with President Ahmadinejad receiving the first-ever official invitation to take part in the Hajj pilgrimage in Saudi Arabia last month.
WHAT TO WATCH FOR: