国家 こっか柱石 ちゅうせきでしょう
kokkano chūsekideshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 国家の柱石

1. Pillar of the nation; Likely a national pillar; Probably a mainstay of the country

Polite
Presumptive
Conjecture