U.S. President Donald Trump said on Sunday that he would depart for Hanoi on February 25 for his second meeting with Kim Jong Un, the top leader of the Democratic People's Republic of Korea (DPRK).

 "I will be leaving for Hanoi, Vietnam, early tomorrow for a Summit with Kim Jong Un of North Korea (DPRK), where we both expect a continuation of the progress made at first Summit in Singapore," Trump tweeted.

Trump hailed his "great relationship" with Kim, adding that the DPRK could "fast become one of the great economic powers anywhere in the World" in the absence of nuclear weapons.

According to the official Korean Central News Agency (KCNA), Kim left Pyongyang on Saturday afternoon by train for Hanoi for the summit.

Trump told the press on Wednesday that his trip to Vietnam would be "very successful," anticipating his two-day meeting with Kim would "accomplish a lot."

Trump announced on Feb. 8 that his second meeting with Kim would take place in Hanoi on February 27-28. His first meeting with Kim in Singapore in June resulted in improved U.S.- DPRK relations.

However, differences on such key issues as a roadmap for denuclearization, the lifting of sanctions and whether to issue a war-ending declaration still hinder negotiations.

Vietnam is also busy in preparing for Trump-Kim summit. Some lamp posts on Hanoi's tree-lined streets are decked with DPRK, U.S. and Vietnamese national flags fluttering above a handshake design, and security has been stepped up at locations that might be a summit venue, or where the leaders might stay.

Prime Minister Nguyen Xuan Phuc has ordered that security should be a top priority for the summit, Vietnam's government said in a post on its website.

(CGTN's Han Peng also contributes to the story)