U.S. Secretary of State John Kerry is headed for home after making clandestine journeys to Iraq and Afghanistan, where he delivered a stern warning to Iraqi leaders about Syria and sought to patch up differences with Afghanistan's president.

Kerry was flying back to Washington on Tuesday from Paris, having piggy-backed off President Barack Obama's trip to the Middle East to make unannounced stops in Baghdad and Kabul. In Iraq on Sunday, he told Prime Minister Nouri al-Maliki that shipments of Iranian weapons and fighters through Iraqi territory must stop. In Afghanistan on Monday, he put on a show of unity with President Hamid Karzai, whose recent anti-American comments had angered U.S. officials.

During the trip, Kerry also held meetings with Israeli and Palestinian leaders and saw Pakistan's army chief.