Seoul, Tokyo and Washington have agreed to take what they're calling "intolerably strong punitive measures" against Pyongyang in the event of further "strategic provocations". 

South Korean representative Kim Hong-kyun briefed journalists after talks on Tuesday with senior diplomats Joseph Yun of the US and Kenji Kanasugi of Japan. Kim said the three countries agreed on the need to focus on maintaining and reinforcing pressures and sanctions against Pyongyang. Kim also mentioned that he discussed ways to gain cooperation with China and Russia on the matter. 

"We agreed that in the current situation where the DPRK remains unchanged regarding nuclear disarmament, we need to focus on leading the DPRK to nuclear disarmament by maintaining and strengthening our stance of pressuring and sanctioning the DPRK.” Said Kim.

Washington's Yun said the US will discuss any action on the DPRK with its allies in the region first. Yun said they don't believe the nation is ready to move towards denuclearization, and the US will continue to work closely with China.

"We believe China has a very very important role to play. We are encouraging especially after the summit between President Trump and President Xi in Mar-a-Lago that China has taken some steps, so we will continue to work very closely with China.” Said Yun.