Saudi officials “were shocked” by the Scud attack, Al-Muslimi a visiting scholar at the Carnegie Middle East Center in Beirut, told bloomberg.

“I don’t think anybody knows how many missiles the Houthis have,” Gregory Gause, a professor of international affairs at Texas A&M University, said.

Satellite imagery shows the Houthis repositioned some of the Yemeni army’s 300 Scud missiles and directed them at Saudi Arabia, a Persian Gulf diplomatic official claimed in March.

Saudi Arabia and neighboring Persian Gulf states, including the United Arab Emirates, spent billions of dollars over the past decade boosting their missile defenses with the latest upgrades of the Raytheon Co.-built Patriot and other anti-missile systems but Ansarallah Scud changed the game.

The Yemen bombing campaign began two months after King Salman ascended to the throne in Saudi Arabia in January following the death of his brother King Abdullah. Since then, he shuffled his cabinet twice and named his son, Prince Mohammed Bin Salman, as WAR minister and deputy crown prince, making him second in line to the throne.

The new Saudi leadership is really invested in this war. So something needs to come out of this for them and for Mohammed Bin Salman, in particular.

The Saudi military said on Saturday shot down a Scud missile fired into the kingdom from Yemen. Saudi troops also repelled an attack on the border. Four Saudi soldiers lost their lives in the battle, state-run media reported.

The Scud attack marked an escalation in the two-month conflict and undermined Saudi Arabia’s announcement in April that it had destroyed the Houthi missile arsenal. The coalition retaliated by bombing the people in Sana’a, killing more than 40 people, according to the Saba news agency.

Saudi Arabia, has said its military campaign in Yemen seeks to restore the rule of ousted and former President Abdurabuh Mansur Hadi. The kingdom and its allies have portrayed the Houthis as tools of Shiite-ruled Iran, a claim viewed with skepticism by European and U.S. diplomats, Bloomberg reports.

The Ansarullah Popular Committee forces are being aided by part of yemen army have taken over large swaths of the country, a small oil producer but one located on an important oil transit route.

Saudi air raids on Yemeni cities of Amran and Saada left scores of civilian’s dead, as the 75-day-long Saudi war on the country has claimed the lives of more than 4,430 civilians.