I can't convince anyone it isn't CGI, ... Actually, I went to the Czech Republic and found a guy who owns, privately, 100 Russian T-72 tanks. It was no problem to lend them to me, but he needed them back to sell to Libya. I also had to inform NATO we were filming there. Someone in the Pentagon could have been looking at satellite images and noticed an arms buildup.
I actually had to deal with real arms dealers to get the film made, to get all [the] guns needed for the movie. When a guy said 'I can deliver you 50 tanks' one private guy who owned 50 tanks in the Czech republic and 'I'll get them there on Tuesday at 9 a.m.,' sure enough, there they are all [were] perfectly lined up.
Normally what you do is that you start with three tanks and you would use replication and you computer generate the other tanks, ... But here, they were so available I could use real tanks. It was cheaper to get real tanks in the Czech Republic than to make the fake ones that I would normally use computer generated imagery to do. In fact, we had to call NATO and warn them about that scene, because it looked like a weapons build-up in the Czech Republic.