STORY: "I, as president, swear upon my honor and integrity before the great Turkish nation and history to safeguard the existence and independence of the state," Erdogan said during a ceremony at the parliament in Ankara, which was broadcast live.

Turkey's longest-serving leader, Erdogan won 52.2% support in a May 28 runoff vote. His election victory defied most opinion polls and came despite a cost-of-living crisis that was seen to have hurt his prospects.

His new five-year mandate allows Erdogan to pursue the increasingly authoritarian policies that have polarized the country, a NATO member, but strengthened its position as a regional military power.