A Ukrainian drone crashed into one of Russia’s largest oil refining complexes on Saturday, sparking a fire and causing minor damage, a Russian official said.

The attack drew widespread international condemnation, including from Gulf monarchies allied with the United States, Israel’s main backer.

In recent weeks the military has primarly targeted high-rise buildings, saying they were being used by Hamas militants.

“The evil-doers responsible for my husband’s assassination have no idea what they have done,” she said in a live video address.

The latest blow to faltering diplomacy came as Russia’s army staged major military drills with its key ally Belarus.