"North Korea's not going to change the way they do business unless they believe that the military option's on the table", Graham, R-S.C., said on "Sunday Morning Futures".
North Korean leader Kim Jong Un met Singaporean Prime Minister Lee Hsien Loong at his office in Singapore Sunday evening in his first diplomatic outing of his visit to the country ahead of Tuesday's landmark summit with U.S. President Donald Trump.
When asked if there was a discussion of pulling the roughly 28,000 U.S. troops out of South Korea, Trump said the topic never came up.
"The Reality TV-Star Trump just pulled off the photo-op of a lifetime", said Beatrice Fihn, executive director of Nobel Peace Prize 2017 victor International Campaign to Abolish Nuclear Weapons.
"Many people in the world will think of this as a. form of fantasy. from a science-fiction movie", Kim said, according to a translator.
The president said he now "trusts" Kim Jong Un and knows now he wants to make a deal, meaning more summits could be held in Pyongyang and Washington.
"Very good, very good".
The handshake, the menu, the positioning of flags - every aspect of the meeting between US President Donald Trump and North Korean leader Kim Jong Un has been dissected and analyzed in the world's media. "I know a lot about airplanes, and it's very expensive", he said.More news: Kim Trump summit: Leaders meet in Singapore
The two will huddle alone for roughly 45 minutes before being joined by aides for a larger meeting and working lunch.
Asked whether he would invite Kim to the White House, Trump said: "Absolutely, I will".
Ms Leong added both found it hard to hide their nervousness once they were seated, with Trump displaying a slanted smile, and fidgeting with his hands and Kim leaning and staring at the ground.
Cheers in South Korea and a one-page "extra" edition of a Japanese newspaper greeted Tuesday's unprecedented summit between Donald Trump and Kim Jong Un.
Mr Trump's delegation at the luncheon included US National Security Adviser John Bolton, Secretary of State Mike Pompeo, White House Chief of Staff John Kelly and Press Secretary Sarah Huckabee Sanders.
Pompeo stressed that the Trump administration would only accept complete denuclearisation of the North.
In the past, it has also been an easy destination for the North Korean elite. "Both the American as well as the North Koreans are pleased with the arrangements, we're all set to go and things will start happening within the next 24 hours".
"If diplomacy does not move in the right direction, those measures will increase", he said.