Leadership isn’t shown just in what you do. It’s shown in what you don’t do.

President Trump proved this recently when he went to Hanoi, Vietnam, to meet with North Korean leader Kim Jong-un and — if all had gone well — forge a deal that would lead to the denuclearization of one of the most dangerous regimes in the world.

But it was not to be. “Sometimes you have to walk,” the president later said. “This was just one of those times.”

It couldn’t have been easy, though. The pressure on a president to forge historic agreements such as this one — especially ones that reduce global tensions and promote peace — is obviously enormous. High expectations could induce any president to waver and consider signing even a bad deal to avoid the specter of a “failed summit.”

The real failure, though, would have been accepting a flawed agreement. The fact that Mr. Trump didn’t do that undercuts the persistent image of him as an impulsive leader willing to say or do anything. If that criticism were fair, he likely would have accepted the bad deal that Kim Jong-un tried to push on him.

“Trump correctly emphasized principles and longtime allies over a premature peace declaration and his newfound relationship with Kim Jong-un,” said Bruce Klingner, former CIA Korea deputy division chief. “It appears North Koreaoffered only its Yongbyon nuclear facility in return for removal of all sanctions.” That, of course, was unacceptable.

Even Senate Minority Leader Chuck Schumer couldn’t fault Mr. Trump this time. “I was pleased to see the president recognize North Korea’s unwillingness to strike a comprehensive deal,” he said. “President Trump did the right thing by walking away and not cutting a poor deal for the sake of a photo op.”

The benefits of rejecting a bad agreement go beyond the Korean peninsula. China’s president, Xi Jinping, can’t miss what this means for U.S.-China relations — namely, that when it comes to intellectual property theft, cyber violations and forced tech transfers from American companies, the U.S. is not about to be bullied.

It isn’t just in Asia that the Trump administration is taking the right steps. Consider Venezuela, where Nicolas Maduro’s regime represents a clear threat to U.S. interests and regional stability. Vice President Mike Pence, who has taken the lead there, has done a great job.

Mr. Maduro is, quite simply, a thug — one whom President Obama and Secretary of State John Kerry apparently couldn’t handle. He came to power in 2013 and distinguished himself by such humanitarian gestures as blocking aid from coming into his country, and burning food and medical relief — in the process of turning his country into a socialist hellhole.

The Trump administration has done much to discredit Mr. Maduro, though. Dozens of other nations have joined us in recognizing the new post-Maduro administration of Juan Guaido.

Now’s the time to move ahead with further sanctions on Venezuela’s state-owned oil company, Petroleos de Venezuela, S.A. All of Mr. Maduro’s cronies and their families are living the high life in Paris, Madrid and even Miami. It’s time we stopped allowing them to enjoy the fruits of kleptocracy.

From North Korea to Venezuela, Team Trump is taking action. The president and vice president, along with Secretary of State Mike Pompeo and National Security Adviser John Bolton, are not only cleaning up messes created by earlier administrations. They’re charting new and positive courses for the future.

As President Trump often says, no option is off the table. His agenda is simple: Do what’s in America’s interest. “America First” doesn’t mean “America Alone.” But it does mean ensuring that our interests aren’t sacrificed on the Altar of the Photo-Op.