To the human eye, not necessarily to detection devices. And, if you are flashing IR you might use a broader range of frequencies that overlaps the visible spectrum (most likely scenario if this was a camera sweep). Also, filters for various frequencies of light can alter those frequencies while blocking and reflecting them, making camera lenses reflect in the visible range. Lots of different things could be going on.
I only commented on the “infrared strobe” because the article stated it. What I was a getting at is this: The red lights are most definitely not inside the White House. They are reflections on the monitor screen.
On the north front of the White House, second floor, west end, there are four windows (as pictured in the video linked in this article).
The window on the far right is in the family kitchen. The next 2 adjacent windows are in the family residence dining room.
The red lights supposedly inside the White House would then be in the kitchen, and in half of the dining room.
Just to the right of the kitchen window, in midair there is a large whitish reflection on the monitor screen, and further to the right there a four large green bars reflected. Thus, the red flashing lights are reflections on the monitor screen that coincidentally appear to be from inside the windows (although a small portion of this red reflection covers the outer wall next to the second window from the right).
Just an FYI: I checked these devices on internet after seeing this story. Several had red bulb indicators. I assume flash when a bug is found. Not that I think that is what’s happening here. The simple answer is usually the best. Accidentally triggered alarm?
But the article is exactly about what the human eye saw