President Trump is right not to close down the federal government. But his abrupt change of mind here won't assist his North Korean diplomacy.

I get what you're probably thinking: "How on Earth are the shutdown threat and North Korea related?"

Both issues speak to the credibility of Trump's threats. Just last week, Trump was meeting with top Democrats and pledging that he would shutdown the government unless Democrats gave him $5 billion for his border wall. Trump was resolute, stating that he would take the blame for the shutdown were it to occur.

Whether or not you agree with Trump, this was strong leadership: clearly stated threats in pursuit of a clear objective.

Then, on Tuesday, White House press secretary Sarah Sanders explained that "We have other ways that we can get to that $5 billion. At the end of the day, we don't want to shut down the government, we want to shut down the border."

Trump thus went from the president who is willing to roll the dice to the president who folds via intermediaries.

This brings us to North Korea. When it comes to addressing North Korea's nuclear and ballistic missile programs, President Trump cannot afford to have Pyongyang see his threats as false. Instead, when the president makes a pledge or a threat to Kim Jong Un, he must be taken at his word. North Korea's understanding of a binary choice between threat and opportunity is exactly what got Kim Jong Un to the table in the first place. It is my firm belief that the North Koreans are only considering a grand compromise with the U.S. because they believe Trump is willing to use military force against them if they do not. Up until now, Trump has skirted clearly between the present overt respect he shows Kim and his previous threats.

Unlike some analysts, I believe it was of instrumental diplomatic value that Trump was willing to make the most extreme of threats to the North Koreans. Doing so, Trump educated Kim to the fact that he is master of the escalatory curve.

Now, Trump's mastery of the curve is in doubt.

But Trump's shutdown about-face is also terribly timed. After all, the president's change of course comes at the most crucial of times in the North Korean diplomatic effort. Kim Jong Un has not decided whether to embrace Trump's offer of compromise or to return to the brinkmanship of 2017. But with U.S. patience rightly running low, the time for a return to credible threats is approaching rapidly.

This credibility concern matters greatly. Foreign actors, especially of Kim's Machiavellian form, watch U.S. presidents to see if their words match their actions. President Barack Obama shredded his foreign policy on the back of a red-line not enforced. Trump must not make the same mistake. If Trump is unwilling to follow through on major threats, he should stay silent.