Reuters has a slightly different take on this:

> Three U.S. military officials, speaking on the condition of anonymity, said U.S. Customs and Border Protection had been using the technology without issues before Tuesday's shutdown and expressed confusion as to why the shutdown was deemed necessary. [0]

It was definitely the army [1] who fired the laser causing the shutdown of El Paso airport, but the army doesn't seem to understand the alarm on the part of the FAA, because DHS (Border Protection) has been using it for some time now without the same alarm from the FAA. Someone at the FAA reacted differently to this army firing than they had to previous DHS firings.

[0] https://www.reuters.com/world/us/senator-says-el-paso-airpor... [1] https://www.reuters.com/business/aerospace-defense/aeroviron...