It was that you knew you had to, because, in the late 1940s, country after country in Central Europe was falling into the Soviet bloc, and so you knew you'd no choice.
そうせざるを得なかったのです 1940年代後期は中央ヨーロッパ諸国が次々と ソ連側に陥っていったので 他に選択がなかったのです