I guess the answer to my question was "twice"

Nice to see somebody still has a little sense in this administration:

The U.S. military launched Tomahawk cruise missiles against radar sites in Yemen early Thursday, a senior defense official said.
The strikes followed two incidents this week in which missiles were fired at a U.S. Navy ship from a rebel-controlled area of the country.

Can't believe we had to get shot at twice before we shot back.