MINSK, Belarus—Western governments are moving to shore up the authoritarian, independent-minded President Aleksander Lukashenko of Belarus, worried that his country’s possible absorption by Russia would alter Europe’s balance of power.

That support, however, is limited by fears that getting too close to Minsk could provoke a Russian intervention. Some commanders in the North Atlantic Treaty Organization say Belarus’s military and security services have already fallen under Moscow’s sway, anyway.

Mr. Lukashenko, in power since 1994, is resisting Moscow’s growing demands to further integrate the two countries into a “Union State,” an entity that has been largely symbolic since its creation 22 years ago. He has rejected Russian President Vladimir Putin’s request to permit Russian military bases in Belarus and has remained neutral on the war in neighboring Ukraine, where the Western-backed government is fighting against Russia and its proxy forces.

“The situation is serious in the sense that Russia may really force them to unite. They are under pressure and now it is the time for the European Union, for Poland, other countries, to support their sovereignty,” said Foreign Minister Jacek Czaputowicz of Poland, a member of NATO and the EU that borders Belarus.

The U.S. and EU, after ostracizing Mr. Lukashenko for years for the suppression of democracy and human rights in Belarus, are resuming high-level contacts, including a visit in August by President Trump’s then-national security adviser, John Bolton.