Question: The Battle of Aden International Airport broke out when Army units loyal to former president Ali Abdullah Saleh attacked an airport in which country?
Sentence (from "Yemeni Civil War (2015–present)"): Houthi forces controlling the capital Sana'a and allied with forces loyal to the former president Ali Abdullah Saleh have clashed with forces loyal to the government of Abdrabbuh Mansur Hadi, based in Aden.
Relevant evidence: No