Some two million Muslim pilgrims are in Saudi Arabia for the annual hajj, or pilgrimage, to Mecca. The hajj is one of the five pillars of Islam, and all Muslims are called to perform it at least once in their lifetime if they are able to do so. Saudi officials have strengthened security and crowd management after last year’s deadly stampede. The Saudi government says 769 people were killed, but other estimates put the death toll at over 2,400. Iran has strongly criticized Saudi Arabia’s handling of the tragedy, and Iranian pilgrims are not taking part in this year’s hajj. Saudi Arabia has accused Iran of politicizing the sacred event.