Hezbollah troops, among the best trained and equipped in the Middle East, have been helping the Assad regime in the fight. Margaret Warner reports from Lebanon on the various sectarian and regional conflicts motivating Hezbollah's participation in its neighbor's conflict…

In Syria, Assad government troops pushed to retake a strategic town close to the Lebanese border. Hezbollah fighters joined the Syrian regime army in laying siege to Qusayr, home to 40,000 civilians. Judy Woodruff reports on the growing involvement of…

April was the bloodiest month since 2008 in Iraq, where widespread sectarian violence killed more than 700 people. Coordinated attacks were responsible for most serious string of violence since American troops left that country almost 18 months ago. Ray Suarez…