NEW YORK (Reuters) – U.N. Secretary-General Antonio Guterres regrets that North Korea has severed hotlines with South Korea, warning that such channels “are necessary to avoid misunderstandings or miscalculations,” a U.N. spokesman said on Wednesday.

Pyongyang’s decision, announced by the KCNA state news agency on Tuesday, marks a new setback to stalled efforts to persuade North Korea to give up its nuclear weapons.

U.N. spokesman Stephane Dujarric noted that June was a symbolic month representing the second anniversary of the first meeting between U.S. President Donald Trump and North Korean leader Kim Jong Un and the 20th anniversary of the first meeting between the leaders of the two Koreas.

“The Secretary-General hopes that all parties use the June anniversaries to redouble efforts to resume talks to achieve sustainable peace and the complete and verifiable denuclearization of the Korean Peninsula,” Dujarric said.

North Korea has been subjected to U.N. sanctions since 2006. They have been strengthened by the 15-member Security Council over the years in a bid to cut off funding for Pyongyang’s nuclear and ballistic missile programs.