Former White House chief John Kelly revealed a number of issues in which he disagreed with President Donald Trump, including isolation files, North Korea and immigration.

Kelly, who served as chief of staff to the White House until January 2019, criticized some of Trump's decisions and statements. This came in a dialogue Wednesday with students at Drew University in New Jersey, reported by "The Atlantic".

The chief of staff at the White House is a very important position in the American presidency, as he is considered the right arm of the president and is often the actual coordinator of administration activities.

Kelly was asked about the dismissal of Lieutenant-Colonel Alexander Vendman from the National Security Council after he testified as part of an investigation into President Trump's removal.

Kelly considered that he "did exactly what he learned throughout his career (...) to inform his officials of what he heard" after seeing something "suspicious", referring to the telephone call of Pete Trump and the Ukrainian president. Vendemann was responsible for US policy toward Ukraine on the National Security Council.

On the North Korean leader, whom Trump met three times, he estimated that he would "never give up his nuclear weapons."

"The president tried (...) but it didn't work out. I am naturally optimistic most of the time, but I'm also realistic, I never thought Kim would do anything other than manipulate us, and he did it effectively."

Kelly answered a question about immigrants coming to America, as he considered that "most of them are good people (...) not all are rapists and murderers."

Although he was known to defend a tough immigration policy, Kelly considered it "not right to portray them that way. I have disagreed with the president (about that) several times."

Before becoming Trump's senior adviser to the White House in July 2017, the retired Marine general served as interior minister during the first six months of Trump's presidency.