Sunday’s crescent moon signals start of Ramadan.

DUBAI, United Arab Emirates — Officials saw the crescent moon Sunday night in Saudi Arabia, home to the holiest sites in Islam, marking the start of the holy fasting month of Ramadan for many of the world’s 1.8 billion Muslims.

The sacred month, which sees those observing abstain from food and water from sunrise to sunset, marks a period of religious reflection, family get-togethers and giving across the Muslim world. Seeing the moon Sunday night means Monday is the first day of the fast.

Saudi state television reported that authorities there saw the crescent moon. Soon after, multiple Gulf Arab nations, as well as Iraq, Syria and Egypt followed the announcement to confirm they as well would start fasting on Monday. Leaders also shared messages of congratulations the month had begun.

However, there are some Asia-pacific countries like Australia, Brunei, Indonesia, Malaysia and Singapore, that will begin Ramadan on Tuesday after failing to see the crescent moon. Oman, on the easternmost edge of the Arabian Peninsula, similarly announced Ramadan would begin Tuesday. Jordan will also begin Ramadan on Tuesday.

This year’s Ramadan comes as the Middle East remains inflamed by the ongoing Israel-Hamas war in the Gaza Strip. That’s raised fears that the conflict may spark unrest far beyond the current borders of the war.

Saudi King Salman specifically pointed to the Israel-hamas war in remarks released to the public after the Ramadan announcement.

“As it pains us that the month of Ramadan falls this year, in light of the attacks our brothers in Palestine are suffering from, we stress the need for the international community to assume its responsibilities, to stop these brutal crimes, and provide safe humanitarian and relief corridors,” the king said.