U.S. Vice President Joe Biden has held separate phone calls with Cypriot President Nicos Anastasiades and Turkish Cypriot leader Mustafa Akinci to urge them to resume settlement negotiations, the White House said.

Anastasiades canceled scheduled peace talks and cut short a visit to Turkey on Tuesday after a United Nations summit treated the rival Turkish Cypriot leader as a head of state.

Biden encouraged Anastasiades to “seize the moment to negotiate a settlement that would reunify Cyprus as a bizonal, bicommunal federation,” the White House said in a statement on Wednesday.

“Subsequently, the Vice President spoke to Turkish Cypriot Leader Mustafa Akinci to convey the same message,” urging both leaders to resume meetings as soon as possible.

Biden “pledged continued U.S. support to both sides” over the Mediterranean island’s reunification, the statement added.

Cyprus has been divided since August 1974. Long-stalled U.N.-brokered peace talks began in May 2015, with the leaders meeting regularly since then.

Anastasiades said Wednesday he won’t tolerate the United Nations’ “bad handling” or allow the island nation’s internationally-recognized government to be “downgraded.”

Cypriot government spokesman Nicos Christodoulides said earlier that the U.N. is “mostly responsible” for what happened because it had given assurances Akinci wouldn’t be there.

Akinci’s spokesman called Anastasiades’ decision to call off Friday’s meeting “a big mistake.”