Laser with 500 kilowatts of power will be in service with the US Navy. In the 2020 powerful laser guns can shoot down ballistic missiles and aircraft in short pulses.
The US Navy in 2012 began to SSL-TM program to create a powerful laser weapons with industry leaders such as BAE Systems, Northrop Grumman, and Raytheon. By 2016 the company created a combat laser power up to 150 kW. It's enough to bring down a small boat, light missile or drone, but for destruction of ballistic missiles or light armored vehicles do not have enough power. Also, these lasers can not instantly kill an enemy soldier, and yet are inhumane weapons.
Only the laser power of 300 kW can effectively destroy antiship ballistic missiles. By 2020, the US Navy is going to experience more powerful lasers - up to 500 kW. This power is sufficient to destroy any missile weapons at a distance of tens of kilometers, as well as to destroy aircraft, helicopters and boats.
Thus, the military approach to the desired power for the laser guns - 1 MW. Guns with such power will be able to deal with almost any targets other than the strongest fortifications. It will evaporate living targets in seconds. Highest accuracy and instantaneous energy delivery to the target compensates many laser’s disadvantages, such as relatively low power and beam scattering in the atmosphere. We can say with confidence that laser and rail gun will replace the conventional artillery guns in the US Navy by mid-century.