Ah yes: before there are further questions...
Yes, contrary to the Trump Admin, the gov in Riyadh, and all sorts of Messiahs on the FB, Twitter and similar platforms, I am convinced that such ballistic missiles like Burkan-2H fired by the Houthis on Saudi Arabia are of something like 'local origin'.
Yemen bought significant numbers of R-17E/SS-1 Scuds from Soviet Union in the late 1970s and 1980s, and then a number (certainly more than 50) of Hwasong-6s from North Korea, in late 1990s and early 2000s.
Now, when the Houthi-Saleh coalition came into being, in period September 2014 - March 2015 - up to 60% of the Yemeni military followed Saleh and joined the Houthis.
With other words: the Houthi-Saleh coalition has got the know-how and the tools to operate such missiles.
The Saudi-led coalition then launched its intervention and - between others - repeatedly targeted bases of the three former brigades of the 'Missile Brigades Group' of the Yemeni Army, in April 2015. Many of ballistic missiles were damaged during these air strikes; some destroyed.
After discussing related issues with some of local sources, plus an Iraqi expert (an engineer involved in the al-Hussein project), my conclusion is that the Burkan-2s are repaired Hwasong-6s. Some were rebuilt with help of various spares smuggled in from Iran.
For further details, see the coming book 'Hot Skies over Yemen, Volume 2: Aerial Warfare over Southern Arabian Peninsula, 1994-2017', and the collection of links here: https://medium.com/@x_TomCooper_x/my...m-1c77f37ab1cd
The illustration below shows (from top towards bottom): Hwasong-6, Burkan-1, Burkan-2. (Haven't drawn any Burkan-2Hs yet, though). The crest in the upper left corner is that of the 'Missile Force' operated by the coalition of the Houthi- and ex-YA-forces that sided with them.