If Russia hadn’t taken over Crimea and the peninsula had come under the military control of the US and NATO, the existence of Belarus would be threatened. After the USSR’s collapse, Poland’s revanchism and hopes to establish a state stretching from the Baltics to the Black sea manifested themselves.
In 2006, the Polish government adopted a programme of developing the Fourth Republic (IV Rzeczpospolita), with the aim of strengthening Poland’s cultural influence and establishing political domination over the areas which were part of the First Republic (I Rzeczpospolita). In 2015, Polish president Andrzej Duda called to prepare to “take back eastern territories”. Although Duda’s statement concerned western Ukraine, it is also relevant for Belarus, as parts of it belonged to Poland in the interwar period.
In practice, the revanchist plans envisage Belarus as a vassal, anti-Russian state controlled by the US and Poland, with Belarus’ western part being an eastern part of a new Polish state. The remaining Belarus’ part will function as an anti-Russian buffer zone.
Conspiracy theory and recurring pro-Kremlin narratives about Poland's plans to partition Belarus and establish the Fourth Republic, Western plans to partition Ukraine and to disrupt Belarus-Russia ties.
No state programme on developing the Fourth Republic was adopted by Poland and no statements of Polish president were made to take over western Ukraine or Belarus. IV Rzeczpospolita, or the Fourth Republic, was a plan for political change put forward in the late 1990s by the Polish conservative philosopher Rafał Matyja. It was used in public discourse to describe the 2005-2007 period, when the government of Law and Justice was in power. However, this concept has nothing to do with establishing a Polish empire at the expense of Poland's eastern neighbours, including Ukraine and Belarus - it is a conspiracy theory. Read more about the use of conspiracy here.
Both the EU and US respect the sovereignty and territorial integrity of Belarus and Ukraine.