"Great to be back from Vietnam, an amazing place. We had very substantive negotiations with Kim Jong Un - we know what they want and they know what we must have. Relationship very good, let’s see what happens!" Trump tweeted.

In another tweet Thursday, Trump had thanked Party chief and State President Nguyen Phu Trong, Prime Minister Nguyen Xuan Phuc and the "wonderful" people of Vietnam for "generously" hosting the event in Hanoi.

The second summit between Trump and Kim ended Thursday with no deal signed because of disagreements over lifting of the sanctions imposed on North Korea.

In separate press conferences following the summit, both sides provided contradicting information on the challenges they faced.

Trump said that North Korea wanted the sanctions "lifted in their entirety, and we couldn’t do that."

But North Korean Minister of Foreign Affairs Ri Yong-ho said Pyongyang had brought a "realistic proposal" to the second summit, requiring removal of just five of 11 sanctions that have imposed great suffering on its economy and citizens.