United Nations Secretary-General Antonio Guterres said that there is no alternative to the two-state solution on Wednesday after US President Donald Trump recognized Jerusalem as Israel’s capital.

Trump has instructed the Department of State to move the US embassy there from Tel Aviv.

“In this moment of great anxiety, I want to make it clear: there is no alternative to the two-state solution. There is no Plan B,” Guterres told reporters at UN headquarters in New York.

Guterres said that Jerusalem is an issue that must be resolved through direct negotiations between Israel and Palestine.

He said that it is only by realizing the vision of two states living side-by-side in peace, security and mutual recognition, with Jerusalem as the capital of Israel and Palestine, and all final status issues resolved permanently through negotiations, that the legitimate aspirations of both peoples can be achieved.

“For my part as the UN secretary-general, I will do everything in my power to support the Israeli and Palestinian leaders’ return to meaningful negotiations and to realize this vision of a lasting peace for both people,” he said.

China voiced concerns about a possible escalation of tension in the region.

Trump said he has judged this cause of action to be in the best interest of the US and the pursuit of peace between Israel and the Palestinians.

The Jerusalem Embassy Act passed by the US Congress in 1995 required the relocation of the US embassy in Israel from Tel Aviv to Jerusalem. Former US presidents, including Bill Clinton, George W. Bush and Barack Obama, all renewed a presidential waiver to delay the relocation. Trump renewed the waiver in June for six months.