"At the three-nation summit, the leaders will hold in-depth discussions on ways to strengthen the three countries' close cooperation in dealing with the North Korean nuclear and missile issues, and enhance their cooperation with the global community", an official said earlier.
North Korea has called increased United Nations sanctions a "hostile act", committed with the intention to "physically exterminate" its citizens.
"President Trump and President Moon committed to continuing to take steps to strengthen deterrence and defense capabilities, and to maximize economic and diplomatic pressure on North Korea", the White House said in a statement.
U.S. Ambassador to the United Nations Nikki Haley now says multiple military options are on the table.More news: Japan Deploys New Missile Defence System To Counter North Korea Threat
"Definitely, there is no military solution there, no doubt that if any military operation is carried out, unfortunately, North Korea's authorities will fulfill those possibilities that they have", Kosachev stressed.
Earlier, the top United States diplomat gave an interview to the program Face the Nation on CBS saying that "if our diplomatic efforts (on North Korea) fail though, our military option will be the only one left". It was the country's longest-ever test flight of a ballistic missile.
In a frank assessment, the former naval leader warned that strong deterrence would carry the risk of miscalculation leading to conflict because the closed-off Kim Jong-un regime can't be trusted to correctly interpret moves by the US and its allies.
She confirmed President Donald Trump's threats of "fire and fury" towards North Korea was no bluff, days before he is due to speak to the UN General Assembly in NY on Tuesday.More news: Zeman meets South Korean President in NY
President Moon Jae-in and first lady Kim Jung-sook wave before departing for the United States, at Seoul Air Base in Seongnam, south of Seoul, on September 18, 2017. Many analysts expect North Korea to dominate Trump΄s speech on Tuesday night at the UN General Assembly.
In this photo provided by South Korea Defense Ministry, U.S. Air Force B-1B bombers, F-35B stealth fighter jets and South Korean F-15K fighter jets fly over the Korean Peninsula during a joint drills, South Korea on Monday, Sept. 18, 2017. "But actually, these kinds of actions didn't help solving the problem but further complicate the situation, which do no good to the resolution of the peninsular issue".
The China Daily yesterday said that sanctions should be given time to bite and that the door must be left open to talks.
In their phone conversation held Sunday, Moon and Trump stressed the need to thoroughly implement U.N. Security Council resolutions that have been imposed on North Korea, including the latest sanctions resolution adopted early last week to punish the communist state for its latest nuclear test.More news: Kenya Supreme Court says why it annulled presidential poll