South Korean Prime Minister Lee Nak-yon said that it's time for North Korea to show its commitment to denuclearization by responding to Washington's "big proposal." 

The prime minister made the remarks on Wednesday during a parliamentary interpellation session at the National Assembly regarding the second summit between U.S. President Donald Trump and North Korean leader Kim Jong-un in Hanoi last month. 

Lee said it appears the U.S. made a big proposal during the summit to realize the complete denuclearization of North Korea, but that the North was not ready to respond. 

In regards to the U.S.' reported demand that North Korea dismantle its Yongbyon nuclear site and additional facilities, the prime minister said while it was a bigger request than expected, Seoul considers it a positive sign that the two leaders both assessed their talks as productive and substantial.