he was opposed to the policies of władysław sikorski toward the soviet union, for example the sikorski-mayski agreement, which he criticized in his writing. together with wacław jędrzejewicz and henryk floyar-rajchman, matuszewski co-founded the national committee of americans of polish extraction (knapp) and the józef piłsudski institute of america. he worked to persuade polish public opinion in the u.s. to oppose the policy of concessions to joseph stalin.