Well Belarus is a long way from the United Kingdom. It's a former part of the USSR (which was never in my backyard either) and has never been a member of the EU, so brexit doesn't enter into it. Geographical distance and backyardery are not quite the same thing, taking political allegiances and the method of governance into account as well as proximity. I'm sure you don't regard the countries on the north coast of South America as being in YOUR backyard (they mostly wouldn't like it either).

As for what's happening on the Belarus/Poland border, Lukashenko has given "tourist visas" to potential refugees from Syria and Iraq, positively inviting them in, enabling them to cross the country easily via Minsk to the Polish border. He's done this in retaliation against EU sanctions. Whatever you think of Poland's response, make no bones about who's responsible for this.

And you often tell me that I don't "get" the politics of YOUR backyard...