The author most likely thinks that:

Choices:
A. North Korea doesn't like what Bolton said
B. not enough information
C. That the US is firm on its demands
D. North Korea may pull out of the summit
North Korea may pull out of the summit
SEOUL — North Korea’s sudden threat to pull out of the upcoming summit with the U.S. raises new doubts of whether a denuclearization deal is possible.
North Korean leader Kim Jong Un agreed to meet with U.S President Donald Trump in Singapore on June 12 to work out an agreement to end the North’s nuclear program in exchange for security guarantees and an end to punishing international sanctions.
But on Wednesday North Korea’s Vice Foreign Minister Kim Kye Kwan released a statement through the state-run KCNA news agency that criticized “unbridled remarks” made specifically by the U.S. president’s National Security Adviser John Bolton demanding that Pyongyang completely decommission its entire nuclear arsenal, along with its ballistic missile program and chemical weapons stockpile, before receiving any compensation or concessions.
He expressed “indignation” at the U.S uncompromising position and said North Korea might pull out of the Trump-Kim summit, unless the Trump administration acts with “sincerity” to improve relations through dialogue.
“If the United States is trying to drive us into a corner to force our unilateral nuclear abandonment, we will no longer be interested in such dialogue and cannot but reconsider our proceeding to the North Korea-U.S. summit,” the statement said.
The vice foreign minister also said it was “absolutely absurd” that Bolton would compare Libya’s experience dismantling its relatively rudimentary nuclear program as a model for dealing with the North’s more advanced and expansive capabilities.
He also denounced the Trump administration for “miscalculating the magnanimity” of Kim Jong Un’s decision to suspend further nuclear and missile tests, and his willingness to engage in nuclear talks, as “signs of weakness,” that were the result of what the U.S. administration has dubbed its “maximum pressure” campaign that led international efforts to impose punishing sanctions banning 90% of North Korean trade.
The vice minister’s remarks came shortly after the North abruptly canceled inter-Korean talks planned for Wednesday, citing ongoing joint military drills between South Korea and the U.S.
Last week American and South Korea forces began their two-week Max Thunder exercise that involves 100 aircraft, including eight F-22 radar-evading jets, as well as F-15 and F-16 fighter jets. The North derided the drills as a rehearsal for invasion that undermines improving inter-Korean ties.