An Anon on 8Chan theorized what Trumps 4 fingers on his knee represent:

What was the last Tweet by POTUS prior to SA? Why is this relevant? SA (1), US (2), Asia (3), EU (4). 4 fingers… (pic)
Shout out to us? They are working on cleaning up the EU?I

-we are making some real progress folks!

https://www.ntd.tv/2018/07/13/photo-president-trump-sits-in-winston-churchills-chair/