The lawsuit came three days after a similar case by NPR, which also saw its funds cut.
Advocates say Trump administration appears to be following Project Esther's recommendations to crackdown on activism.
In his campaign-style speech, Trump also hailed a 'blockbuster agreement' between Japan's Nippon Steel and US Steel.
If election frontrunner Lee Jae-myung is elected, Sejong city could replace Seoul as the centre of political power.