Ethiopia had only just emerged from 20 years of war with neighbouring Eritrea, when its prime minister, Abiy Ahmed launched a brutal new conflict in the northern Tigray region. For two years, the Ethiopian army - this time supported by Eritrean forces - fought Tigray's ruling party. An estimated 600,000 people were killed. Now tensions are ratcheting up again. Ethiopia is the world's most populous landlocked country, and Abiy Ahmed is demanding access to the sea, putting pressure on Eritrea, aft