(CNN) As President Donald Trump prepares to meet face-to-face with North Korean leader Kim Jung Un for a second time, his administration is weighing backing off an earlier demand that North Korea agree during the upcoming summit to make a full accounting of its nuclear and missile programs as a prerequisite for US concessions, multiple administration officials tell CNN.

The administration has been pressing North Korea since the two leaders' last summit in Singapore to provide information about its nuclear capabilities, suggesting such an accounting would be a necessary outcome of any second encounter between Trump and Kim.

As recently as November, Vice President Mike Pence called such a nuclear accounting an "imperative" at a second summit.

"I think it will be absolutely imperative in this next summit that we come away with a plan for identifying all of the weapons in question, identifying all the development sites, allowing for inspections of the sites and the plan for dismantling nuclear weapons," Pence said.

Now, administration officials describe such a declaration as a longer-term goal of the talks.

"Eventually we are going to need a full declaration in order to complete the process of denuclearization," a senior administration official told reporters Thursday. "I expect that will come well before the end. And it is basically the international standard on how one can go about addressing the issue of elimination of weapons of mass destruction."

Trump administration negotiators, led by special representative Stephen Biegun, are in Hanoi ahead of Trump's meeting working to strike an agreement with North Korea on a joint declaration for the two leaders to sign during their talks. Officials said there were a number of options under discussion but refused to describe what they might be.

"Nothing will be agreed to until everything's agreed to," one official told reporters.

Concerns Trump could offer Kim too much

Inside the White House, some advisers have privately raised concerns that Trump could offer too much to Kim at the summit, which he insisted upon after his first meeting in June garnered widespread media attention.

In that meeting, Trump shocked top advisers by agreeing to cancel joint US-South Korea war exercises, which was seen as a major concession to Pyongyang. Aides have speculated what surprises might be in store this time around as Trump looks to prove that his diplomatic effort is moving forward.

That could include a formal peace declaration ending the Korean War, an option Trump has found attractive because it carries historic weight and would allow him to tout his role as a peacemaker. He's thirsted after a Nobel Peace Prize, and said last week that Japanese Prime Minister Shinzo Abe had nominated him for the award, though he cast doubt the committee would recognize him.

Ending the war would have uncertain repercussions. Trump has long agitated about the cost of US troops in South Korea, leading some advisers to fret he could order their withdrawal. However, officials said this week that pulling American service members from South Korea was not a topic of discussion with the North Koreans.

Most of Trump's advisers have low expectations for the talks. Many have cautioned Trump that his second meeting is unlikely to generate as much interest as the first, which was historic in nature since no US president had ever previously met with a North Korean leader.

Similarly, many advisers have cast lower expectations for what concessions North Korea is prepared to offer to move toward denuclearization.

"I don't know that there's real high expectations for anything substantial for something to come out of the meeting," a person close to the White House said, saying that many inside the West Wing do not expect "anything earth-shattering" to come out of the summit.

"There are very tempered and cautious expectations on what may come out of this," the person said. White House officials view the second summit as a "next step," but don't anticipate it will result in much progress toward denuclearization.

Speaking Friday, press secretary Sarah Sanders said the summit's success lay in its mere existence, which she said was an indication of thawing relations between Washington and Pyongyang.

"The only one setting high expectations is probably the media, because they're looking for reasons to attack this president," she said on Fox News. "They hate the idea that he's done so well on something his predecessors couldn't do anything on. He's had great success here in the fact that they were even able to sit down at the table. The fact that he's able to do it again is in itself a big success."

How much to demand and how soon

As Trump has pushed somewhat reluctant aides to schedule the second summit with Kim, some internal rifts have opened between members of his national security team over how much to demand from North Korea and how soon.

Since assuming his post over the summer, Biegun has drawn private skepticism from other members of Trump's national security team, according to officials familiar with the matter. As Trump continues to press for agreements with North Korea that can demonstrate progress, some officials have expressed concern that Biegun may be overly willing to take steps that would satisfy the President's desire to make a deal, and not encourage tough demands from Kim.

He said during a closely watched speech at Stanford University last month that North Korea expects their steps toward dismantling some enrichment facilities should be met with "corresponding measures" from the US, and he was set to find out which exact measures they were thinking about — a different approach than demanding complete denuclearization before taking reciprocal action.

As Biegun proceeds with his diplomatic efforts, he has told people he is looking to maintain US principles in the talks while also allowing for a degree of flexibility to prevent North Korea from walking away from the table, as they have done multiple times in the past. It's an artful approach, people familiar with his strategy say, that amounts to balancing the President's demands with finding openings for progress.

This week's meeting could determine which strategy wins out, officials said, describing the diplomacy at "a critical juncture."

The consideration of backing off an immediate demand for a nuclear accounting coincides with a broader change in how administration officials are characterizing the standard for success in the upcoming summit.

On NBC News this week, Secretary of State Mike Pompeo said that some US sanctions would be removed when "We're confident we've substantially reduced that risk" from North Korea's nuclear weapons program. In June of last year, at the time of the first Trump-Kim summit, Secretary Pompeo tied sanctions relief to full denuclearization.

"We are going to get complete denuclearization; only then will there be relief from the sanctions," Pompeo said in June.