When I worked in counter-intel I often went to West Berlin. There about every other person you met was a spy for one side or the other. Great parties, though.
I got into uniform and went into East Berlin all according to Hoyle. I had a camera and took some neat pictures of the architecture. Of course, the polizei had to come and harass me. I told them to piss off and get a Russian officer, which was according to the treaty. The polizei weren’t squat in East Berlin if you were an American in uniform. I kept walking about and a Russian officer approached me and was polite. GRU, naturally. We chatted and sat in a bistro and had beer and sandwiches, which I paid for. We talked and both agreed it would be sad if we ever had to go to war against each other as we had more in common than with most of our allies. Rather charming fellow. We played it according to the rules and he asked what I was photographing, I told him the buildings and that I wasn’t stupid enough to photograph military things out in the open with the polizei watching me like a hawk. We both laughed. I left him with a spare Zippo lighter with a naked woman on it and two packs of unfiltered Camel cigarettes. I had already gotten the message I went in to get. He walked me to the checkpoint and had them wave me through without issues. All gentlemen and friends.