[391][392]

Trump, King Salman of Saudi Arabia, and Egyptian president Abdel Fattah el-Sisi at the 2017 Riyadh summit in Saudi Arabia
Saudi Arabia
Trump actively supported the Saudi Arabian–led intervention in Yemen against the Houthis and in 2017 signed a $110 billion agreement to sell arms to Saudi Arabia,[393] In 2018, the USA provided limited intelligence and logistical support for the intervention.[394][395] Following the 2019 attack on Saudi oil facilities, which the U.S. and Saudi Arabia blamed on Iran, Trump approved the deployment of 3,000 additional U.S. troops, including fighter squadrons, two Patriot batteries, and a Terminal High Altitude Area Defense system (THAAD), to Saudi Arabia and the United Arab Emirates.[396]

Syria
Trump ordered missile strikes in April 2017 and in April 2018 against the Assad regime in Syria, in retaliation for the Khan Shaykhun and Douma chemical attacks, respectively.[397][398]
In December 2018, Trump declared "we have won against ISIS," contradicting Department of Defense assessments, and ordered the withdrawal of all troops from Syria.[399][400] The next day, Mattis resigned in protest, calling his decision an abandonment of the U.S.'s Kurdish allies who played a key role in fighting ISIS.