They've been saying this for years. Nothing new.
Every time new sanctions are approved on North Korea, the U.S. government comes out and pushes this same agenda that NK has nukes already.
In 2012 we expanded sanctions on North Korea. Here's a story on that:
U.N. Council to Expand North Korea Sanctions
Here's a story from 2012, right after sanctions imposed, saying North Korea likely already has nuclear warheads
And what's going to happen again, in the next year or so,
as happened in 2013, is China & Russia will be found to have been violating the new sanctions. Same cycle every 5-7 year, same storyline. Social engineering
