Mixed success for Saudi military operation in Yemen
On 22 April, following a month of military operations involving 2,415 sorties and the release of at least 1,000 air-to-ground weapons, Saudi Arabia's bombing campaign in Yemen, Operation Decisive Storm, was brought to a close.
In its place a new phase of operations known as Operation Restoring Hope was put into action, stressing a reduction in the use of force and a movement to a proposed political solution.
Saudi Arabia has operated at a virtually unprecedented volume of military activity that, in tandem with its coalition partners, managed a remarkably sustained level of air strikes for a number of weeks.
Certainly, Saudi Arabia has shown an ability to conduct a high volume of air strikes (sometimes as many as 125 strikes a day), proving wrong those that doubted the Kingdom's ability to sustain complex extra-territorial operations.
The munitions used by the Royal Saudi Air Force (RSAF) point to a preference for relatively small payloads between 500-2,000lb, with a heavy focus on GPS and Laser guided gravity bombs.
The success achieved by the RSAF in hitting military targets was high, and initially the precision munitions caused little collateral damage.
This is primarily due to the choice to target military installations, which, by their very nature, tend to be placed away from civilian areas.
The targeting order made sense: first to be hit were Yemeni Air Force installations, ballistic missile sites, and ammunition dumps, followed by identifiable Houthi military convoys and concentrations of fighters.
However, the longer Decisive Storm went on and the fewer defined targets remaining that showed clear military purpose, the more collateral damage and incorrect target identification occurred.
The Houthis, like so-called Islamic State, got better at concealing their activities, the result being that strikes increasingly erred in accuracy and caused civilian casualties.
In addition the Saudis have operated a tight restriction on the flow of shipping and aircraft into Yemen, blockading ports around Hudayda, Aden and international airports in Sanaa, Taiz, and Aden.
The primary aim being to stop Iranian supply shipments to Houthi rebels from entering the conflict zone.
The blockade achieved its intended purpose, but recent attempts by Iran to run the exclusion zone, by sending planes to Yemen supposedly for "humanitarian" reasons, have been met by Saudi force that verges on disproportionate, such as the bombing of runways at Sanaa International Airport.
So has the Saudi operation been a success? Yes and no.
If the definition of success is the removal of strategic and tactical threats to the Saudi homeland, then yes the Saudis basically achieved their aims.
Who is fighting whom?
The Houthis: Zaidi Shia-led rebels from the north, who seized control of Sanaa last year and have since been expanding their control
President Hadi: Fled to Saudi Arabia after rebel forces advanced on his stronghold in the southern city of Aden
Al-Qaeda in the Arabian Peninsula (AQAP): Seen by the US as the most dangerous offshoot of al-Qaeda, AQAP opposes both the Houthis and President Hadi
Islamic State: A Yemeni affiliate of IS has recently emerged and seeks to eclipse AQAP in the region
Almost all Yemen's potentially offensive capabilities have been destroyed and the armed forces fighting on behalf of the Houthis and former President Ali Abdullah Saleh pose no more than mild irritant to the Saudi state.
However, if Decisive Storm is judged in terms of achieving political solutions then the answer is far less clear.
The Houthis have not retreated from the south of the country nor have they been backed into a position in which they appear willing to take a seat at the negotiating table under terms that either President Abdrabbuh Mansour Hadi or his Saudi backers can accept.
Bracket of security
The movement to Operation Restoring Hope is designed to afford the Saudis time to achieve this result, in this sense.
Although air strikes are ongoing the stress here is that Restoring Hope is not primarily a military-led campaign, if anything it is merely a bracket of security around which a political settlement can be achieved.
Yet the Saudi political machine has tried to show that the operation has been a success.
The Defence Minister and newly promoted Second Deputy Prime Minister, Mohammed bin Salman, has taken ownership of this war and he cannot fail to achieve success politically, even if the military gains are somewhat suspect.
As such, it's unlikely that Riyadh will report Operation Decisive Storm and Operation Restoring Hope as anything other than military successes which achieved a defined objective.
The Saudis are unlikely to be able to move back to the operational levels that were used in Decisive Storm.
Wear on airframes, munitions stocks and servicing requirements take their toll on aircraft flying daily sorties over target areas.
Additionally the amount of valuable, easily identifiable targets to hit in Yemen has reduced to virtually zero.
Far more likely is a sustained, lower intensity close air support campaign which will look to provide back-up units operating on the ground against the Houthis, adapting quickly to battlefield conditions.
It is unlikely that total military victory under these conditions can be achieved, and furthermore it is unrealistic to expect the RSAF to provide the killer blow.
If the rag tag assortment of forces on the ground in Yemen cannot push the Houthis back then the conflict will sadly drag on for months to come.
Michael Stephens is Research Fellow for Middle East studies and Head of Rusi Qatar