President Donald Trump declared North Korea a state sponsor of terrorism on Monday even as his top diplomat said Washington has not given up hope of a negotiated end to its nuclear standoff with Kim Jong-Un’s regime.

Trump promised a rapid ramp-up of US Treasury sanctions against the pariah state, after adding its name to a terror blacklist previously led by Iran and Syria.

“Should have happened a long time ago. Should have happened years ago,” Trump declared, citing the death of a US student who had been held in a North Korean jail and the assassination by nerve agent of Kim’s elder half brother on foreign soil as reasons for the move.

But, speaking to reporters after the cabinet meeting, Secretary of State Rex Tillerson said Washington has not given up hope that sanctions and diplomacy can pressure Kim into agreeing to sit down and discuss his nuclear disarmament.

Tillerson said that punitive measures were already having a “significant effect” on Pyongyang’s economy — even if China has yet to cut off oil supplies to its sole refinery — and said: “We still hope for diplomacy.”

There was no immediate reaction from Pyongyang, but an editorial that appeared in the ruling party newspaper Rodong Sinmun before Trump’s announcement described the president as a “mentally deranged money-grabber” who was leading the United States down an “irretrievable road to hell.”

Both Trump and Kim have previously raised fears of open conflict erupting over the North’s banned nuclear missile program, with both insulting and threatening the other with a devastating military response.

But US officials have also been clear that their main hope is that what Tillerson described as an inexorable increase in economic and diplomatic pressure, backed by China,will force Pyongyang to back down.