President Donald Trump has now taken the tensions with North Korea to new heights, tweeting on Friday morning that the US military is in position to attack North Korea at a moment’s notice.

“Military solutions are now fully in place, locked and loaded, should North Korea act unwisely,” the president wrote. “Hopefully Kim Jong Un will find another path!”

This is deeply alarming: Trump is sending a signal to Pyongyang that any US military activity nearby — like long-planned military exercises with South Korea set for August 21 — might well be cover for an attack. That makes the North more willing to consider preemptively striking US and South Korean forces, which would be a catastrophe.

But even worse, Trump’s tweet is actually false: The US military is not “fully in place” and ready to start a war with North Korea.

Doing so would require deploying a huge number of new military assets beyond what the US currently has stationed in South Korea and East Asia. And the Pentagon confirms that no such deployments have happened.

“No,” Lt. Colonel Christopher B. Logan, a Pentagon spokesperson, told me over the phone. “No changes related to that [North Korea].”

So this is a double whammy of a bad tweet: It’s a lie, and it’s a lie that makes a very serious threat that the US military is not quite ready to deliver on.

Why Trump’s tweet is so irresponsible

North Korea’s military, while outclassed by the combined might of the United States and South Korea, is still one of the world’s largest — boasting 1.2 million active service members, 7.7 million reservists, and roughly 21,500 artillery pieces (many of which are pointed right at Seoul, home to 10 million people and South Korea’s capital). Being “fully in place” for a strike on North Korea would mean deploying ground troops to the region that could reinforce the South’s defenses and bringing in aircraft carrier groups that could neutralize the North’s Navy and Air Force.

None of that is happening right now. In fact, two US carriers — USS Carl Vinson and USS Ronald Reagan — just left the waters near North Korea in June.

This is not what you’d expect to see if the US military were, as the president puts it, “fully in place” for a North Korea strike. My colleague Jennifer Williams puts it well:

If we were really about to launch a massive, bloody war with North Korea that could potentially kill tens of thousands of innocent civilians in South Korea and elsewhere — one war game convened by the Atlantic magazine back in 2005 predicted that a North Korean attack on the South would kill 100,000 people in Seoul in the first few days alone, while others put the estimate even higher — one would expect to see a major mobilization happening across the political, military, and diplomatic arms of the US government. We’re not seeing anything like that. What we do have is a belligerent statement from President Trump that he made while on vacation in New Jersey.

This isn’t the first time Trump has radically misstated America’s military position with respect to North Korea. In April, he asserted that “we are sending an armada, very powerful” to the North’s coast. At the time, the “armada” he was referring to — the Carl Vinson’s carrier group — was actually 3,500 miles away, and heading in the opposite direction from North Korea.

But this time is much more dangerous. Tensions with the North, owing to North Korea’s missile tests and Trump’s unprecedentedly aggressive rhetoric, are at an all-time high. And the more belligerent statements the president makes, the more fraught the situation gets.

Typically, the US deters North Korean aggression by setting clear and predictable policies. Everyone in the US government is on the same page, making it clear to Pyongyang what they can get away with and what will be met with a US response. Public statements are especially important signaling, because the US doesn’t have a direct line of communication with North Korea. The Kim regime figures out what America is saying through US public statements, making consistency in that messaging all the more important.

The more aggressive those messages are, the more likely the North is to react badly.

Trump’s words could “lead Pyongyang to miscalculate or believe it needs to act preemptively if it believes a US attack is imminent,” Laura Rosenberger, the former National Security Council director for Korea and China, told me earlier this week. “Those consequences could be catastrophic.”