The socialist fraternal kiss was a special form of greeting between socialist state leaders. The act demonstrated the special connection that exists between Communist countries, consisting of an embrace, along with a series of three kisses on alternate cheeks. In rare cases, when the two leaders considered themselves exceptionally close, the kisses were given on the mouth rather than on the cheeks.
Here is a photo of a Soviet and an American soldier sharing a ‘socialist fraternal kiss’, Germany, 1945:
That mural on the Berlin wall is very popular in tourist shops there.
The NATO themed gift shop near Checkpoint Charlie has a really large collection of items with the image plastered on. Was surprising, to say the least.