Millions of watts of peak intensity is commonplace.
Its the trillions of watts that are a tricky to build.
That's why I don't think what you're saying passes the sniff test. If it were as easy as you say, SDI wouldn't have been the massive technological undertaking it was realized to be. They were talking about power levels in excess of 10 exp 16 watts! As for pulses, the question is one of total aggregate energy. But if that much energy can be absorbed in the atmosphere (as was the case with SDI) then I would suspect that the total energy delivered would also have to be astronomical to get through all that air. If it were as easy as you suggest, Reagan could have equipped the SDI satellites with lasers from Radio Shack.