The historic diplomatic encounter planned for three weeks from now between President Donald Trump and North Korean despot Kim Jong Un appeared in doubt on Tuesday as Trump questioned whether preparations could be completed in time.
Trump raised doubts about the summit in talks on Tuesday with South Korean President Moon Jae-in, who came to Washington to urge Trump not to let a rare opportunity with reclusive North Korea slip away.
The North announced earlier this month that it planned to "completely" destroy the Punggye-ri facility in the country's mountainous northeast.
This satellite image, released and notated by Airbus Defense & Space and 38 North on March 30, shows the Punggye-ri nuclear test site in North Korea.
"There are certain conditions that we want", Mr Trump said.
Lu said China had played a positive role on the Korean peninsula, after Trump reiterated his suggestion that Kim's recent meetings with Chinese President Xi Jinping had influenced Kim to harden his stance ahead of the summit.
There was no word on how the South Korean reporters might reach North Korea to catch up with their colleagues.
Also wary of possibilities of any unexpected friction with the North, the South Korean government gave the activists a permission to travel to the off-limit areas only a few days before the Saturday event, the organizers noted.
"Both in terms of building the trust and confidence between the United States and North Korea (DPRK) to be successful, but also in terms of working through the mechanics of denuclearization", Stangarone said. Others say North Korea has learned all it needs from the nuclear tests conducted there.
He did not detail the conditions he had laid out for Kim but said if they aren't met, "we won't have the meeting".
Go Myong-hyun, an analyst at the Asan Institute for Policy Studies, said both sides were playing "a game of chicken" in the run up to the summit "to gain an upper hand in negotiations".
"North Korea has a chance to be a great country and it can't be a country under these circumstances they are living right now", Trump said.
"North Korea can say to the worldwide community that it did its best to achieve denuclearisation through negotiations but was pressured by the United States and couldn't do it", he said.
They reported that they were leaving their hotel in the coastal city of Wonsan at about 5.30pm local time.
A small coterie of foreign reporters has set off on a marathon journey to a remote location in North Korea to witness Pyongyang's purported destruction of the Punggye-ri nuclear test site.
National security adviser John Bolton, who has been outspoken in his hawkish views toward North Korea, drew Pyongyang's ire when he suggested Trump use a so-called "Libya model" to rid the country of its nuclear weapons. The South's presidential Blue House declined to comment on the implications for family reunions, referring questions to the Unification Ministry.
What did Mr Pompeo say?
Pompeo defined "denuclearization" as Trump's goal for North Korea to eliminate its nuclear weapons arsenal, and its capacity to develop and deliver such weapons.
"Do we really need denuclearisation as a premise for unification?" she said.