Washington (CNN) President Donald Trump's scrapping of the Iran deal he inherited raised the stakes for a North Korean agreement he hopes to build, a contradiction over two aspiring nuclear powers that pose the biggest foreign policy challenge yet for his administration.

The President didn't wait for his critics to link Iran and North Korea. He proudly made the connection himself, standing in the Diplomatic Reception Room on Tuesday, declaring: "Relationships are building. Hopefully a deal will happen."

And he announced that Secretary of State Mike Pompeo was flying to Asia for his second face-to-face meeting with North Korean officials, tasked with setting up a summit between Trump and Kim Jong Un.

But the President's thirst for a nuclear deal of his own made him vulnerable to repeating one of his sharpest critiques of the Obama administration: being so eager to strike a bargain with Iran took away considerable leverage and resulted in a weaker agreement. Even as the President cast his predecessor as overly willing to strike a deal in a bid to polish his legacy, some administration officials quietly fret Trump may himself be similarly eager for a deal on North Korea.

Trump has insisted he won't settle for anything resembling the agreement President Barack Obama signed on to along with US allies. He has repeated his pledge to stand up and walk out of the talks if they deteriorate. But Trump has become more invested by the moment, a worrying sign for Trump aides who have expressed misgivings over the President's enthusiasm for a deal.

Changing circumstances?

Last week Trump insisted a location and date were set for the summit and would be announced soon. He repeated that assertion after his remarks on Tuesday. But Pompeo appeared to walk that claim back aboard his plane.

"We think we have it figured out," he told reporters as he jetted toward North Korea. "We'd love to be able to walk away from here prepared to say, 'Yep, we now have the senior level, most senior leaders' commitment to this date and this location.' "

It was the latest indication that Trump may be out ahead of his aides in gunning for an agreement with the hermit regime.

He agreed to meet Kim Jong Un on the spot when presented with the invitation in the Oval Office by a South Korean envoy in March. He later expressed a desire to meet at the Korean Demilitarized Zone, where he said a celebration could be had if talks were successful, despite objections from top aides that it could appear he was traveling to Kim's doorstep. And he touted the imminent homecoming of three American prisoners in North Korea before any agreement on their release was finalized.

"We've been asking for the release of these detainees for 17 months," Pompeo said aboard his plane. "We'll talk about it again. It'd be a great gesture if they'd agree to do so."

On Tuesday, Trump's aides argued the President's decision to quit the Iran deal only strengthened his hand with North Korea, suggesting he was willing to walk away from a weak agreement.

"I think the message to North Korea is the President wants a real deal," said John Bolton, the US national security adviser. "When you're serious about eliminating the threat of nuclear proliferation, you have to address the aspects that permit an aspiring nuclear weapons state to get there. The Iran deal did not do that. A deal that we hope to reach, the President is optimistic we can reach with North Korea, will address all those issues."

Steeper challenge

Yet in many ways, disarming North Korea of its nuclear weapons will provide a far steeper challenge for Trump than convincing Iran to curtail its nuclear program. Both countries have concealed their ambitions for years, but North Korea's arsenal is far greater and more advanced than Iran's. North Korea has openly flouted its arsenal of nuclear warheads, while Iran insists its nuclear facilities were for civilian purposes only.

Trump has not detailed what demands he will place on North Korea when he sits for talks with Kim, beyond insisting upon "complete denuclearization." But calling on the country to dismantle its production facilities or relinquish its weapons will require a far more expansive inspections regimen to verify than in Iran.

As Trump delivered his remarks, which were carefully watched around the world on Tuesday, two words were not directly mentioned: President Obama. Yet the fact that his predecessor negotiated the deal has always made it a deal-breaker for Trump, just as Obama-era agreements on climate and trade found themselves in the same trash bin.

While Obama went unmentioned by name in Trump's remarks, a fundraising email sent by his campaign hours afterward left little question of his motivations.

One veiled reference from Trump to Obama, "when I make promises, I keep them," raised one of the most consequential questions of all: Can the word of the United States be trusted from one President to another?

In a statement on Tuesday, Obama did not directly mention Trump either , but delivered one of the biggest rebukes he's given to his successor.

"The consistent flouting of agreements that our country is a party to risks eroding America's credibility," Obama said, "and puts us at odds with the world's major powers."

By pulling out of the Iran deal, Trump touched off a chorus of criticism from alumni of the Obama administration and allies across the world. In near unison, many argued that the prospect of a North Korea deal suddenly seemed even more difficult.

Tony Blinken, a former deputy secretary of state who helped negotiate the Iran deal in 2015, said Trump's task with North Korea is now more daunting.

"Having thrown out an agreement the Iranians were complying with, why should Kim Jong Un believe a word that (Trump) says when they actually start to negotiate? Why should he believe anything we put on paper if we're prepared to tear it up?" said Blinken, now a CNN analyst.

"By decrying the Iran deal and saying it's a piece of trash, he has to get a better deal with North Korea to justify it," Blinken said. "Is he going to be able to get the North Koreans up front to dismantle virtually all of their nuclear enterprise? Is he going to be able to get the most intrusive inspections regime in history in North Korea as we did with Iran? That's pretty unlikely."