The BBC report cruise missiles fired from USN ship(s) at land targets, radar stations:
It marks the first time the US has fired at rebel targets since the start of the Yemen conflict in March 2015.
Link:http://www.bbc.co.uk/news/world-middle-east-37639565

The Soufan Group have a longer commentary:http://soufangroup.com/tsg-intelbrie...back-in-yemen/

I do wonder if the Houthi's and allies knew the radar blips were USN ships, knowing firing at USN ships surely would be unwise.