Saudi Arabia claimed it intercepted seven ballistic missiles fired at Riyadh and other cities by the Houthi rebels in Yemen, the biggest such barrage since the kingdom went to war against them in March 2015.
The missiles were intercepted late Sunday over the northeastern part of the capital and the cities of Najran, Jizan and Khamis Mushait, the official Saudi Press Agency said. Fragments killed one Egyptian national and injured two others in Riyadh.
The missile attack was timed to coincide with the third anniversary of the war and the visit of Saudi Crown Prince Salman to Washington.
The Houthi-affiliated Saba news agency said the rebels targeted King Khaled International airport in Riyadh, Abha airport in Aseer and Najran’s airport. Rebels say that the group’s missile force is growing and that it “cannot be intercepted by the U.S. defense systems.”
However, according to a report from CNN, the seven long-range Burqan 2H ballistic missiles were detected by Saudi Arabia’s air force on Sunday. All of the missiles were intercepted and destroyed. However, debris from one of the destroyed missiles had reportedly hit a residential neighborhood along the southern border. Witnesses of the attack posted several videos on YouTube, which included footage of explosions in the night sky. One resident uploaded a video that showed missile debris landing on the highway.
Much of the controversy surrounding this attack centers on the efficacy of the Saudi Patriot anti-missile system. The Saudis said all the missiles were intercepted, but some critics of the Patriot missile system insisted that the Patriot missiles failed to hit their targets. They pointed to one YouTube video showing a Patriot missile making a u-turn after launch and crashing into a residential area.
Modified Missiles and limitations
One of the reasons why the Houthi missiles seem to have more of psychological than destructive military impact is the distance the missiles must travel and the modifications that the Houthis have made to the missiles to reach Riyadh or other strategic targets in Saudi Arabia.
Part of the Houthi ballistic missile attack campaign uses modified missiles from S-75 (SA-2 'Guideline') surface-to-air missile (SAM) systems to create the Qaher-1, which was unveiled in December 2015 and supposedly has a range of 250 km. The Yemeni military had numerous S-75 batteries at the start of the conflict. The liquid-fuel S-75 missiles typically have a 195-kg fragmentation warhead that can be set to detonate before it hits the ground. They are normally used with static launchers, but a rebel video aired on the Al-Masirah television channel on 22 December 2015 appeared to show one being fired from the back of a civilian truck.
The rebels announced on March 28, 2016 that they had launched an improved version called the Qaher-M2 with a claimed range of 400 km and a 350-kg warhead, claiming that three had been fired at King Khalid Air Base. This was supported by a video showing three S-75-type missiles being launched in quick succession. The Saudi coalition confirmed the attack, telling the media that four ballistic missiles had been shot down before they reached Khamis Mushayt (the fourth missile may have been launched from another location). This appeared to be a saturation attack using multiple missiles in an attempt to overwhelm the Patriot battery defending the city.
The rebels have also unveiled new Scud versions, the first being the Burkan-1, which was announced on September 2, 2016. The rebels claimed that it was 88 cm in diameter (the same as an original Scud design), 12.5 m long (more than 1.5 m longer than a conventionally armed Scud), and weighed 8,000 kg with a 500-kg warhead (around 2,000-kg heavier than a Scud although the warhead weighs roughly half as much). According to the rebels, the first Burkan-1 attack was carried out on October 9, 2016 when a missile hit King Fahd Air Base outside the Saudi city of Al-Taif, about 525 km from the Yemeni border. The Saudi coalition confirmed the incident.
In order to increase the range, a new version, the Burkan-2 was developed. The general design of the Burkan suggests that it is a standard Scud that has been lengthened with additional sections welded into its fuselage and fuel tanks so that it can carry the additional propellant needed to extend its range. Iraq carried out similar modifications to produce Al Hussein missiles capable of reaching Tehran during the 1980-88 Iran-Iraq War. There are reports that each Al Hussein was initially made using parts from three Scuds.
The Burkan-2 appears to use a new type of warhead section that is locally fabricated. Both Iran and North Korea have displayed Scud derivatives with shuttlecock-shaped warheads, but none of these match the Yemeni version. The range of the Burkan missiles also appears to have been extended by a reduction in the weight of their warheads. It can be problematic to take too much mass from the nose of a ballistic missile as this shifts the missile's center of gravity in relation to its center of pressure, making it less stable in flight. This was a problem for Iraq's Al Hussein missiles, which tended to break up on re-entry during the 1990-91 Gulf War.
Yemen's rebels may be experiencing similar problems. The first two Burkan-2 missiles launched at Riyadh came down before reaching intended targets. And, as we noted in our analysis several weeks ago after the last attack on Riyadh, fragments of the warhead displayed by the US showed melting, which indicates a failure of the warhead section.
It’s also important to remember that effective warheads aren’t judged by the amount of explosives they contain. They also need material to fragment – and effective shrapnel weighs a lot. Without shrapnel material, the only real damage from the warhead is caused by the explosive shockwave, which dissipates by the cube root as it emanates from the blast. Basically speaking, that means that the explosive energy dissipates by 75% as the distance the shockwave travels doubles (generally speaking as other factors like the altitude of the explosion have an impact too). That’s why fragmentation is so important because it allows the explosive energy to travel further and do more damage. The heavier the shrapnel, the more energy is stored in it. Consequently, the lighter the warhead, the less effective it is.
Houthi missile attacks on the Saudis are more likely to have impact on the Saudi population and question the rational of continuing aggression on Yemen. It is putting the Saudi leadership and MBS in a more embarrassing and negative status, and shows the resilience and creativity of the Yemenis defending their country.