President Putin has said, correctly, that the NK’s would rather eat grass than give up their nuclear weapons. So trade sanctions of whatever sort are futile. The latest threat to halt trade between the US and any country which trades with China is ill conceived and impossible to implement without major damage to US economic interests.
Most NK trade is with China, so to have any semblance of a threat that is not laughable to Pyongyang, the US embargo would have to apply to China. That would be a near disaster to the American airplane industry, American farmers, the info tech industries and more. It would be ignored by the UK, Germany, France and Russia, as well as dozens of other countries, who have trading ties with China. So it is a pointless proposal which will achieve no more than all its predecessor sanctions.
The plain fact is nothing and nobody will stop the North Koreans in their project to obtain nuclear military power, other than their destruction or through negotiations which somehow give them the security they want. Remember in order to get Khrushchev to remove Soviet missiles from Cuba, Kennedy had to pull US missiles out of Turkey. But he judged it a better option than oblivion.
The situation with North Korea has, over many decades, been allowed to get out of control. It is not the fault of the current generation of politicians but it is their call now. There are two options only. Talk or fight. We know what Kennedy chose. That is why we are still here.