MINSK, Aug. 17 -- In May, Andrei Lukyanovich described a difficult military-political situation around Belarus, driven by what he called the unprecedented militarisation of its neighbours, and told the state news agency BelTA that his duty crews were recording violations of the state border in the airspace almost every day. On Sunday the same commander said the situation was stable, that it posed no threat, and that the aircraft and troops facing him across the western frontier had thinned out.

What he announced alongside that assessment is the more consequential part. Belarus, Lukyanovich said, maintains constant operational coordination with Poland, Lithuania and Latvia on mutual notification of flights near the border. Minsk tells the...