Uganda is in a hurry to investigate the kingdom's attack that has killed more than 100 people

KAMPALA, Uganda – The United States and other authorities urge the Ugandan authorities to thoroughly investigate a military attack on the palace of a tribal king two years ago, which killed more than 100 civilians and was largely condemned.

At least 15 children were among the victims of the November 2016 assault on a kingdom known as Rwenzururu, whose leader for years has been politically opposed to Ugandan President Yoweri Museveni, according to Human Rights Watch.

The killings followed clashes between police and supporters of the tribal king, who was later arrested and charged with hundreds of supporters. Many remain in detention.

The United States and the European Union are demanding justice for the victims of the attack whose perpetrators in the police and the army have never been punished.

"How long will they wait?", Said the US statement tweeted on Tuesday. The EU asked for a transparent inquiry.

Uganda insists that the attack targeted armed militia and that the case was before the criminal justice system. No arrests of military actors were announced and the operation's commander, Major-General Peter Elwelu, was later promoted to the rank of commander of the Ugandan land forces.