The United Arab Emirates (UAE), a key member of the Saudi-led coalition fighting in Yemen, is scaling back its military presence there as worsening U.S.-Iran tensions threaten security closer to home, four western diplomatic sources said.

The UAE has pulled some troops from the southern port of Aden and Yemen's western coast, two of the diplomats said, areas where the Gulf state has built up and armed local forces who are leading the battle against the Iran-aligned Houthi group along the Red Sea coast. Three of the diplomats said Abu Dhabi preferred to have its forces and equipment on hand should tension between the United States and Iran escalate further after attacks on oil tankers in the Gulf and Tehran's downing of a U.S. unmanned drone. "It is true that there have been some troop movements ... but it is not a redeployment from Yemen," a senior Emirati official told Reuters, adding that the UAE remains fully committed to the military coalition and "will not leave a vacuum" in Yemen.

In Yemen's civil war, the UAE is part of the Saudi-led coalition battling Iranian-backed rebels known as Houthis, who have taken over most of northern Yemen. The UAE entered Yemen's war in March 2015 alongside Saudi Arabia to back Yemen's internationally recognized government, which the Houthis had pushed out of the capital, Sanaa. The UAE has largely handled ground operations in the conflict while the Saudis have carried out airstrikes. The ongoing war has resulted in the worst humanitarian crisis in the world, with an estimated 24 million people, close to 80 percent of the population, in need of assistance and protection in Yemen, according to the U.N., the World Health Organization (WHO) says some 10,000 people have been killed since the coalition intervened in 2015, but rights groups state the death toll could be five times as high.

Many atrocities have been reported so far, which reveals multiple violations of human rights. Schools and hospitals in the war-torn country have come under frequent attack, threatening the lives of many children. Saudi-led attacks have killed nearly 4,600 out of the 7,000 verified civilians who have died in the war, according to recent figures by the U.N. Human Rights Office. In September, the Saudi-led coalition admitted that mistakes were made in an August airstrike that killed 40 children, an event considered an apparent war crime by the U.N. human rights body. Saudi Arabia's alleged human rights violations are not limited to that country but have expanded beyond its borders, since there is an endless war in Yemen.