Emirates News Agency (WAM) reported that Sheikh Khalifa bin Zayed Al Nahyan has died, and the Emir of Abu Dhabi and the President of the United Arab Emirates (UAE) has died. Sheikh Khalifa was 73 and had been battling illness for several years.

“The Ministry of Presidential Affairs announced that there will be 40 days of official mourning with flags at half-mast and three days closure of ministries and official entities at the federal and local levels and the private sector,” WAM posted on Twitter today.

Sheikh Khalifa had rarely been seen in public since suffering a stroke in 2014, with his brother, Abu Dhabi’s Crown Prince Mohammed bin Zayed (known as MBZ) seen as the de facto ruler and the decision-maker of major foreign policy decisions, such as joining a Saudi-led war in Yemen and spearheading an embargo on neighboring Qatar in recent years.

“The UAE has lost its righteous son and leader of the ’empowerment phase’ and guardian of its blessed journey,” MBZ said on Twitter, praising Khalifa’s wisdom and generosity.

Under the constitution, Vice President and Prime Minister Sheikh Mohammed bin Rashid Al Maktoum, the ruler of Dubai, would act as president until the federal council which groups the rulers of the seven emirates meets within 30 days to elect a new president.

Condolences started pouring in from Arab leaders, including Bahrain’s king, Egypt’s president and Iraq’s prime minister.

US Secretary of State Antony Blinken conveyed his condolences on the death of Sheikh Khalifa, whom he described as “a true friend of the United States”.

“We deeply valued his support in building the extraordinary partnership our countries enjoy today. We mourn his passing, honour his legacy, and remain committed to our steadfast friendship and cooperation with the United Arab Emirates,” he said.

Sheikh Khalifa came to power in 2004 in the richest emirate Abu Dhabi and became the head of state. He is expected to be succeeded as ruler of Abu Dhabi by Crown Prince Sheikh Mohammed.

Abu Dhabi, which holds most of the Gulf state’s oil wealth, has held the presidency since the founding of the UAE federation by Sheikh Khalifa’s father, the late Sheikh Zayed bin Sultan Al Nahyan, in 1971.

World Tourism Network VP for Global Affairs, Alain St. Ange said: “WTN expresses sympathy to family, Government and People of the UAE on the passing of His Highness Sheikh Khalifa, the ruler of the UAE. His Highness was a true architect of his Nation and he will be missed by all friends of the UAE.

“On behalf of the leaders of the WTN from the Community of Nation and on my own behalf please accept sincere sympathy in this difficult period.”