Museveni leveled the criticism in a statement after meeting U.N. officials investigating an ambush of peacekeepers in eastern Congo last month that left 15 dead and 53 wounded.

The Allied Democratic Forces (ADF), a Ugandan Islamist rebel group that has been operating in the chaotic eastern Congo jungles for years, was widely blamed for the attack.

“The United Nations is responsible for preserving terrorism in the Democratic Republic of Congo,” Museveni told U.N. investigators, according to the statement from his office.

It did not elaborate and Museveni’s spokeswoman did not respond to calls seeking an explanation. There was no immediate comment from the United Nations.

The attack was described by U.N. Secretary General Antonio Guterres as the worst on the world body in recent history.

Set up in 2010, the U.N. peacekeeping mission in Congo called MONUSCO is the global body’s largest but has struggled to neutralize a patchwork of rebel and militia factions in eastern Congo and has previously drawn criticism from Museveni.

A few days after the ADF attack, Uganda carried out air and artillery strikes on the group’s camps. Kampala said it had intelligence the rebels were planning hostile acts against it.

The East African country, which has a history of meddling in lawless eastern Congo, is eager to prevent the ADF from re-entering Uganda’s oil-rich western region as the resulting insecurity could force out investors.

Uganda is aiming to start pumping crude in its west in 2020.