The Yemeni army has announced one of the largest military operations in response to Saudi Arabia’s war crimes against its southern neighbor.

A spokesman for Yemen’s armed forces says a joint operation has been carried out involving the country’s indigenously made air and missile capabilities.

Yahya Sara’e says sensitive military sites have been targeted in Southern Saudi Arabia using five ballistic missiles and five armed drones. The spokesperson says the military facilities that have been hit are the National Guard compound in the city of Najran, the King Khalid airbase in the city of Khamis Mushait, and military positions in Abha international airport.

Sana’a has highlighted before that warplanes take off from Abha airport which Riyadh is using to launch airstrikes against residential areas in Yemen. The spokesman added that the missiles and drones hit the designated targets with precision but no immediate details were available regarding possible casualties among Saudi military personnel.

Yemen’s armed forces are expected to expand their military attacks in the coming weeks and months to force Saudi Arabia to end the war on their country and lift the blockade. The operation comes as the country’s forces have made significant advances in Marib, Saudi Arabia’s last major stronghold in Yemen. Heavy clashes have resumed in the flashpoint city as peace talks between the UN and other world powers collapse in Oman.

Over the past two years, the Yemeni armed forces have strengthened their military capabilities and increased retaliatory attacks against Saudi Arabia in response to a deadly war waged by Riyadh on its southern Arab neighbor in March 2015. The almost daily Saudi bombardment has killed hundreds of thousands of Yemenis, many of them women and children. Riyadh backed by Washinton has also imposed an all-out blockade on Yemen that has led to what the United Nations says is the world’s worst humanitarian crisis.