The first group of Iranian pilgrims has departed for Saudi Arabia on the 2017 Hajj pilgrimage, the journey to the holy city of Mecca and Medina that every Muslim is supposed to undertake at least once in a lifetime.

According to Al-Arabiya, the Iranian pilgrims flew out of Bandar Abbas International Airport on Sunday morning, with two more flights close behind. An estimated 86,500 Iranians are expected to travel to Saudi Arabia for the Hajj this year.

Iranian participation in the pilgrimage was not guaranteed this year. None were allowed last year, during a time of high tension between Saudi Arabia and Iran. The decision to allow Iranians was not announced until March.

Not only are there major policy conflicts, and outright proxy wars, between Riyadh and Tehran in places like Syria and Yemen, but the Iranians have been highly critical of how Saudi Arabia manages the annual Hajj event, especially after a 2015 stampede that killed over 2,400 people.

The Saudis have, in turn, accused Iran of politicizing the Hajj. On Monday, for example, Iran’s Supreme Leader Ayatollah Ali Khamenei urged Muslims to turn this year’s pilgrimage into a protest against what he described as “Israeli efforts to control the Al-Aqsa mosque” – a reference to security measures implemented by Israel after a Palestinian terrorist attack. Many Muslim leaders have denounced these measures as a trick by the Israelis to keep Muslims away from the Temple Mount in Jerusalem.

Khamenei also called on pilgrims to express their opposition to “America’s wicked presence in the region.”

The event commonly cited as the reason for excluding Iranians from last year’s pilgrimage was Saudi Arabia’s execution of firebrand Shiite cleric Nimr al-Nimr and the ensuing riot at the Saudi embassy in Tehran. An Iranian appeals court upheld sentences against ten of those rioters on Monday.

Qataris are apparently less welcome than Iranians at the Hajj this year. They have not been banned outright by the Saudi government, but Qatari organizers say they have encountered a number of difficulties with flights, ground transportation, and accommodations.

One Qatari official told Al-Jazeera that Saudi vendors are “reluctant to work with the Qatari Hajj companies, fearing retaliation in light of the sympathy laws that were passed.” The laws in question make it a crime for Saudis to publicly express sympathy with Qatar.  

Al-Jazeera’s article includes some grumbling from Qataris that Iran is being treated better than Qatar at this year’s pilgrimage, despite the fact that one of Saudi Arabia’s chief accusations is that Qatar has been excessively friendly toward Iran. Saudi Foreign Minister Adel al-Jubeir dismissed these complaints and accused Qatar of trying to “politicize the issue,” which he said the Saudi government regards as “disrespectful to the Hajj and pilgrims.”