NAIROBI, Kenya (AP) — Ethiopia’s prime minister has sought to defend a major military action against the country’s defiant Tigray region Sunday, and urged citizens not to target the ethnic Tigrayan people amid fears of civil war.

At least 60 people have been wounded and six killed in one location along the Tigray border alone, Doctors Without Borders said Saturday, and the United Nations warns of a major humanitarian crisis if millions flee all-out fighting or if the Tigray region remains cut off from the world.

Prime Minister Abiy Ahmed tweeted that his military campaign is to bring the Tigray region to abide by Ethiopia's “rule of law.”

“The government’s law enforcement action in Tigray aims to bring the greedy Mekele junta under the rule of law and maintain the constitutional order. This step will benefit the widest Tigrayans more than anyone else,” Abiy tweeted. “I also urge all Ethiopians to take responsibility for ensuring that Tigrayans do not fall prey to any illegal activity that follows the government’s actions.”

The conflict pits two heavily armed forces against each other in the heart of the strategic but vulnerable Horn of Africa region, and experts worry that neighboring countries, including Sudan, Eritrea and Somalia could be sucked in.

Diplomats and others assert that the conflict in Tigray could destabilize other parts of Ethiopia, Africa’s second-most populous country with 110 million people, scores of ethnic groups and other regions that have sought more autonomy even as the Nobel Peace Prize-winning Prime Minister Abiy Ahmed tries to hold the country together with exhortations of national unity.

Communications remain largely cut off in Tigray, with airports and roads closed.

The Tigray leader in a letter to the African Union chair, seen by The Associated Press, has warned that Ethiopian forces are preparing to launch a large-scale offensive.