It Was The Police
They were two police officers! Apparently, the neighbors had called about Brian’s threats the day before. They were not there to solve the issue with the smoke but to warn Brian to desist in his ways.
Brian and Svetlana tried to tell the officers about the problem. But they just shrugged and repeated what the neighbors had said before: there was nothing illegal about burning coal in that part of the country. Now, what could the couple do?