Poland is threatened by the European integration process. It may make Poland lose its sovereignty and become part of a supranational European state.
Recurring pro-Kremlin narrative about the EU as a threat to national sovereignty and disintegrating.
According to the Article 4 of the Treaty on European Union: “The Union shall respect the equality of Member States before the Treaties as well as their national identities, inherent in their fundamental structures, political and constitutional, inclusive of regional and local self-government. It shall respect their essential State functions, including ensuring the territorial integrity of the State, maintaining law and order and safeguarding national security. In particular, national security remains the sole responsibility of each Member State.”
In addition to that, operating on a basis of mutual agreement and cooperation, the EU respects the will of its members to opt-out from certain policies.