This was my inspiration for the infinito.gif contest.
Kissing each other was a common practice between soviet leaders. It was a sign of socialist solidarity. Some images are very known:
Brejnev and Ulbricht’s kiss is known as the “Fraternal Kiss” and was painted in the eastern side of Berlin Wall’s ruins by Dmitri Vrubel, after the collapse.
In Rob Schroder’s film montage, the kiss is counterposed with the break of Berlin’s wall, for it took a month between those happenings. If Brejnev and Ulbricht got along well, the same didn’t happened with Gorbachev, which is taken by many as one of the great responsibles for the end of the Cold War and the dissolution of the Soviet Union.
In this post from another blog, I found the explanation quite simple.