From BBC World Service:

“The major arms that Saudi Arabia buys come from the US and UK. Its air force comes from primarily the US, F-15s and F-16s, but it has also purchased a large number of typhoons. The UK is a main participant in the manufacture and sale of the typhoon. It also supplies training to Saudi forces.”

Other comments on the main enablers of the war: the US and UK have helped with refueling of Saudi bombers, reinforcing the naval blockade, and under Obama the US only pulled back symbolically while still providing support.

Embed from Getty Images

A Saudi Air Force advanced F-15SA fighter jet performs with the Royal Saudi Hawks, the aerobatic team of the Royal Saudi Air Force, during a ceremony marking the 50th anniversary of the creation of the King Faisal Air Academy at King Salman airbase in Riyadh on January 25, 2017.

From The Aviationist:

On March 31st, the Royal Saudi Air Force flew to Sudan to train with the Sudanese. In 2015, Sudan changed their long-standing alliance with Iran to join the Saudi-led coalition fighting the Houthi rebels.