NORTH KOREA OPENS A KEY CHANNEL OF COMMUNICATION WITH SOUTH KOREA EVEN AS IT BATTLES WITH TRUMP OVER THE SIZE OF NUCLEAR BUTTONS. ‘MINE IS MORE POWERFUL AND IT WORKS,’ THE PRESIDENT TWEETED.

SEOUL • North Korean Leader Kim Jong Un reopened a key cross-border communication channel with South Korea for the first time in nearly two years Wednesday as the rivals explored the possibility of sitting down and talking after months of acrimony and fears of war.

The sudden signs of easing hostilities, however, came as President Donald Trump threatened Kim with nuclear war in response to his threat earlier this week.

Trump said his nuclear button is “bigger and more powerful” than that of Kim, teasing the dictator on Twitter that his version actually works. The president’s dismissal was delivered on social media and triggered a split reaction. Supporters praised the “awesome” putdown as a show of strength against a U.S. enemy, while critics questioned the president’s “fitness for office.”

Trump tweeted: “North Korean Leader Kim Jong Un just stated that the ‘Nuclear Button is on his desk at all times.’ Will someone from his depleted and food starved regime please inform him that I too have a Nuclear Button, but it is a much bigger, more powerful one than his, and my Button works!”

It was the president’s fullest reaction to Kim’s New Year’s Day speech in which he said the country already had nuclear weapons that could hit the U.S. Kim, in an apparent two-track strategy, combined his hardline on the U.S. with an offer of negotiations to South Korea, including about North Korea’s participation in the Winter Olympics. Experts said it appeared Kim was trying to drive a wedge between South Korea and the U.S., whose relations have been strained since Trump took office.

South Korea quickly welcomed Kim’s decision and later confirmed that the two Koreas began preliminary contacts on the channel. During their 20-minute communication, liaison officials of the two Koreas exchanged their names and examined their communication lines to make sure they were working, according to Seoul’s Unification Ministry.

Moon Jae-in, the South Korean president, was elected on a platform of opening talks with North Korea last year in an attempt to convince them to stop their nuclear program.

However, Trump’s administration has refused to start talks until Kim abandons his nuclear ambitions and is said to fear his latest comments are a stalling tactic as he builds more weapons.

The president’s mockery of Kim split opinion in the U.S. Michael Flynn Jr, the son of Trump’s former national security adviser, tweeted: “this is just awesome.”

But Norman Eisen, former U.S. ambassador in the Czech Republic, told CNN: “That tweet caused me to question his stability and his fitness for office. He’s making the situation worse.”

In Britain, Theresa May dodged the chance to criticize the comment and instead stressed the need to stop North Korea’s “illegal” nuclear program.