North Korea’s apparent test of an intercontinental ballistic missile puts it closer to having the ability to hit the United States with a nuclear warhead. This is an extraordinarily dangerous development.

I worked on North Korea policy in both the George W. Bush and Obama administrations, at the State Department and on the National Security Council, so I know firsthand just how difficult the challenges posed by North Korea are to deal with. I know how constrained the policy options are, and I’m familiar with the many difficult choices involved in selecting from a menu of bad options. And I know the incredibly complicated coordination — both within our own government, and with our allies and partners — that is necessary to implement a strategy to handle it.

But President Trump’s reaction to North Korea’s missile test was to immediately reach for his phone and sound off with chest-thumping statements on Twitter.  This is a very reckless reaction, and one that risks miscalculation by adversary and ally alike.

North Korea will parse every word of Trump’s Twitter statements to try to understand what they mean. That’s because North Korea uses its own propaganda mouthpieces in an intricate way to signal its intentions to both internal and external audiences. As a government official working on North Korea, I spent hours working with analysts poring over North Korean statements to understand Pyongyang’s thinking — whether and how it differs from past statements — and cutting through the bluster to identify the core point it was communicating. Its words are carefully chosen, and it uses different formulas to send different signals.