Russia has flown two nuclear-capable strategic bombers over Belarusian airspace, a clear show of solidarity with its close ally during a tense standoff with the European Union over its burgeoning migrant crisis. The EU is considering sanctions against Belarus in retaliation for Minsk’s artificial creation of what the UN has called an “intolerable” crisis. Belarus has denied this, and Kremlin spokesperson Dmitry Peskov called a Polish insinuation that the crisis is being directed by Moscow “absolutely irresponsible and unacceptable.”

On Wednesday, Warsaw said that migrants in Belarus tried to force their way into Poland the previous night. Polish authorities reinforced the country’s borders with 3,000 more guards following the nearly 600 crossing attempts on Tuesday. The EU has accused Minsk of sowing “gangster-style” chaos, deliberately gathering and pushing Middle Eastern, Afghan, and African migrants across the Polish border.

“It is apparent that a humanitarian catastrophe is looming against the background of Europeans’ reluctance to demonstrate commitment to their European values,” Peskov said at a briefing, according to Reuters. He accused Europe of attempting to “strangle” Belarus by closing its borders.