BRUSSELS—The European Union will tighten visa rules for Belarusian state officials, Europe’s migration commissioner said on Wednesday, in retaliation for what she called Minsk’s aggressive effort to destabilize the bloc by pushing in illegal immigrants. The EU accuses President Alexander Lukashenko of orchestrating a sharp rise in illegal immigration arrivals across the Belarus border with bloc members Poland, Lithuania, and Latvia. The increase happened after the 27-nation union slapped sanctions on Minsk over human rights abuses and an election widely deemed rigged. “We have an aggressive regime, Lukashenko, that is actually pushing migrants … to the European border to destabilize the European Union,” the bloc’s Home Affairs Commissioner Ylva Johansson told journalists. “This is an act of aggression.” Johansson made the comments as part of an update on stalled efforts to agree a new EU migration system to replace the one that failed amid a 2015–16 spike in Mediterranean immigration. …