Washington (AFP) – Donald Trump and North Korean leader Kim Jong Un headed toward Hanoi on Monday for their second high-stakes summit, with the world watching to see if the US leader can deliver concrete results on curbing the nuclear threat from Pyongyang.Tweeting from Air Force One, Trump said he was “looking forward to a very productive Summit,” after earlier reiterating his case for North Korean disarmament.”With complete Denuclearization, North Korea will rapidly become an Economic Powerhouse,” he tweeted. “Without it, just more of the same.””Chairman Kim will make a wise decision!”The Hanoi summit comes after Trump and Kim met in June in Singapore, producing a vaguely worded agreement on denuclearization, but progress has since stalled, with the two sides disagreeing over what the agreement meant.The summit set for Wednesday and Thursday will present them with a second shot at progress on the world stage.Trump’s departure after noon on Monday came as an armored train carrying Kim and members of his delegation moved southward through China to Vietnam, in a journey cloaked in secrecy.The train station on the Vietnam-China border where Kim was expected to arrive was effectively on lockdown Monday.Sources in Vietnam said Kim could arrive at the Dong Dang border station in the early hours of Tuesday following his epic 4,000 kilometer (2,500 mile), two-and-a-half-day journey.With the two mercurial leaders en route to Hanoi, United Nations Secretary-General Antonio Guterres said he looked forward to the pair reaching key agreements.”I hope that the leaders… agree to concrete steps for sustainable, peaceful and complete and verified denuclearization of the Korean peninsula,” Guterres said in a speech in Geneva.But at a White House event Sunday, Trump appeared to temper any expectations of a major breakthrough, saying sanctions imposed over Pyongyang’s missile and nuclear tests would remain.”The sanctions are on. Everything is on. But we have a special feeling and I think it will lead to something very good. Maybe not,” Trump said.”I don’t want to rush anybody. I just don’t want testing. As long as there’s no testing, we’re happy.”- ‘Strong deal’ sought -Members of Trump’s Republican Party, however, were demanding the president stand tough, with Senator Marco Rubio calling for the US and its allies to “maximize” pressure on Pyongyang, including immediate intensification of sanctions, if there is no breakthrough.”American negotiators must push for no less than a strong deal to completely, verifiably, and irreversibly dismantle the North Korean nuclear and missile programs,” Rubio said in a statement minutes after Trump took off.Pyongyang insists it has already taken appropriate steps by not testing ballistic missiles or nuclear weapons for more than a year and blowing up the entrances to its atomic test site.But at the same time, North Korea says it has completed the development of its arsenal and the facilities are no longer needed.While Pyongyang and Washington have taken guarded approaches to the summit, hopes rose in Seoul that Trump and Kim could formally declare an end to the 1950-53 Korean War, after South Korea said the two leaders could reach an agreement.The devastating conflict between communist North Korea, backed by China, and the capitalist South, aided by the United States, ended with an armistice rather than a peace treaty, leaving Pyongyang and Washington still technically at war.”I believe that the possibility is there,” the South’s presidential Blue House spokesman Kim Eui-kyeom told reporters about a formal declaration.”There is no way of knowing what kind of declaration it might be, but I believe the US and North Korea may reach an agreement.”Trump is expected to arrive in the Vietnamese capital on Tuesday evening local time.