In his sharpest criticism yet of his old workplace, John Bolton suggested the Trump administration is bluffing about stopping North Korea's nuclear ambitions — and soon might need to admit publicly that its policy failed badly.

Driving the news: Bolton told me in an interview that he does not think the administration "really means it" when President Trump and top officials vow to stop North Korea from having deliverable nuclear weapons — "or it would be pursuing a different course."

Why now? The president's former national security adviser, who served until September, is speaking out ahead of an end-of-year timetable. If Kim Jong-un follows through on his threatened Christmas provocation, Bolton says the White House should do something "that would be very unusual" for this administration: admit they got it wrong on North Korea.

"The idea that we are somehow exerting maximum pressure on North Korea is just unfortunately not true," Bolton said.

For example, he said, the U.S. Navy could start intercepting oil that is illegally being transferred to North Korea at sea.

As Bolton sees it, the administration now has more of a "rhetorical policy" that it's unacceptable for North Korea to have nuclear weapons that could hit America or its allies.

If Kim thumbs his nose at the U.S., Bolton said, he hopes the administration will say: "We've tried. The policy's failed. We're going to go back now and make it clear that in a variety of steps, together with our allies, when we say it's unacceptable, we're going to demonstrate we will not accept it."

Bolton described his concerns about Trump's North Korea strategy in an interview with Axios late last week. He went significantly further than any of his previous remarks since leaving the administration.

Why it matters: Kim is back on his white horse, and the North Korean nuclear threat may be greater than ever, analysts say.

North Korea has intimated it will test some kind of advanced weapons in the coming weeks — weapons it's developed as Trump has tried to woo Kim.

Trump's top envoy to North Korea, Deputy Secretary of State Stephen Biegun, said recently that if North Korea follows through on that threat, it would be "most unhelpful in achieving a lasting peace on the Korean Peninsula."

Bolton called Biegun's statement "a late entry but a clear winner in the Understatement of the Year Award contest."

Bolton, who has advocated for a more aggressive North Korea strategy, also criticized Trump for saying earlier this year that Kim's short-range missile tests don't bother him.

"When the president says, 'Well, I'm not worried about short-range missiles,' he's saying, 'I'm not worried about the potential risk to American troops deployed in the region or our treaty allies, South Korea and Japan.'"

The big picture: The imminent threats from North Korea seem a world away from June 2018, when Trump returned from his Singapore summit with Kim to boast, "There is no longer a nuclear threat from North Korea."

In reality, Kim has expanded his nuclear arsenal since then, analysts say.

Using data from analysts and governments around the world, Japan's Nagasaki University estimated in June that Kim now has as many as 30 nuclear warheads. That's on the lower end of estimates, and it's up from as many as 20 warheads in the same study last year.

"Even though they're not testing right now, they're operating at full tempo," said Victor Cha, the National Security Council director for Asia under President George W. Bush and Korea chair at the Center for Strategic and International Studies.

The Trump administration declined to comment.

Between the lines: Daniel Russel, President Obama's assistant secretary of state for East Asian and Pacific affairs, said that of the two leaders —Trump and Kim — only one appears to have had a strategy.

Trump broke with precedent, met twice with the isolated dictator and said "we fell in love" over "beautiful letters."

Russel described Trump's approach to Kim as "magical thinking, based on a narcissistic conviction that the tractor beam of Donald Trump's charisma was going to capture the Leninist dictator and pull him into some kind of condo-developing frenzy of good behavior."

Despite Trump's charm offensive, Kim's nuclear arsenal has only grown.

Trump's warming of relations also signaled to China — the country with the most power to constrain Kim — that it could stop enforcing United Nations sanctions against North Korea, Russel said.

Since Trump's Singapore summit with Kim, North Korea analysts including Russel and Cha have said that the economic pressure on Kim has softened noticeably.

China has turned a blind eye as more money crossed the border into North Korea and more oil was illegally transferred at sea. And last week, China and Russia asked the U.N. Security Council to soften sanctions on Kim.

The bottom line: "We're now nearly three years into the administration with no visible progress toward getting North Korea to make the strategic decision to stop pursuing deliverable nuclear weapons," Bolton said.

"Time is on the side of the proliferator," Bolton said. "The more time there is, the more time there is to develop, test and refine both the nuclear component and the ballistic missile component of the program."

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