US president Donald Trump said he believes North Korea will abide by its pledge to suspend missile tests while he prepares for a summit by May with the North's leader Kim Jong Un.
Mr Trump noted in a tweet that North Korea has refrained from such tests since November and said Kim "has promised not to do so through our meetings".
"I believe they will honour that commitment," the president wrote.
North Korea has not conducted a Missile Test since November 28, 2017 and has promised not to do so through our meetings. I believe they will honor that commitment!— Donald J. Trump (@realDonaldTrump) March 10, 2018
The president continued the optimistic tone on Saturday night when he led a rally for the Republican candidate in a special House race in western Pennsylvania.
When he mentioned Mr Kim's name, the crowd booed but Mr Trump responded: "No, it's very positive ... no, after the meeting you may do that, but now we have to be very nice because let's see what happens, let's see what happens."
Mr Trump shocked many inside and outside his administration on Thursday when he told South Korean officials who had just returned from talks in North Korea that he would be willing to accept Mr Kim's meeting invitation.
Earlier on Saturday, Mr Trump tweeted that China was pleased that he was pursuing a diplomatic solution rather than "going with the ominous alternative" and that Japan is "very enthusiastic" about the agreed-to talks.
Spoke to Prime Minister Abe of Japan, who is very enthusiastic about talks with North Korea. Also discussing opening up Japan to much better trade with the U.S. Currently have a massive 0 Billion Trade Deficit. Not fair or sustainable. It will all work out!— Donald J. Trump (@realDonaldTrump) March 10, 2018
Mr Trump has spoken with both Chinese President Xi Jinping and Japanese Prime Minister Shinzo Abe since Thursday's announcement, and said Xi "appreciates that the U.S. is working to solve the problem diplomatically rather than going with the ominous alternative".
The president had previously threatened North Korea with "fire and fury like the world has never seen".
Mr Trump also said China, North Korea's most important ally and trading partner, "continues to be helpful!" as he has repeatedly urged China to do more to pressure North Korea into abandoning its nuclear program.
He said in another tweet on Saturday that Mr Abe is "is very enthusiastic about talks with North Korea" and that the two discussed how to narrow the US-Japan trade deficit, writing : "It will all work out!"