North Korea really abandons nuclear weapons?

The situation around Korean peninsula is shaking dramatically. Kim Jong-un, the dictator of North Korea declared that he would stop the nuclear experiment.

France 24: North Korea says it no longer needs nuclear tests

According to the North, it has no more needs of nuclear weapon tests. It may mean that the North believe its monarch will survive long without the power of the nuclear weapon. On the other hand, Kim's comment is hardly trustworthy for many foreign leaders.

The US and Trump administration is willing to say that North's abandon of nuclear experiments is the victory of the US' diplomacy. But it seems Trump' intention is different.

The Washington Post: White House privately skeptical of North Korea’s plans to freeze nuclear testing

On the other hand, South Korea is still in a terrible situation. If the US troop is withdrawn from Korea, it will face a fear of unexpected attack of North Korea. Japan is at the same status as South Korea.

South China Morning Post: Kim Jong-un says he’s stopped testing nukes, but can South Koreans trust anything the North says?
http://www.scmp.com/news/asia/east-asia/article/2142748/kim-jong-un-says-hes-stopped-testing-nukes-can-south-koreans

Another possibility is that the financial status of North Korea does not allow further development of the nuclear weapons. If so, sanctions against the North has been effective. Then, gradual approach to the North to modify it to democracy is preferable, if possible.