Trump’s memo stating US ‘shall withdraw’ from UNFCCC marks first time any country has tried to exit the agreement

The Trump administration’s long-anticipated decision this week to pull the US from the world’s most important climate treaty may have been illegal, some experts say.

“In my legal opinion, he does not have the authority,” Harold Hongju Koh, former head lawyer for the US state department, told the Guardian.

In a Wednesday presidential memorandum, the president said the US “shall withdraw” from the UN Framework Convention on Climate Change (UNFCCC), along with 65 other organizations, agencies and commissions that it deemed “contrary to the interests of the United States”. It marks the first time any country has ever moved to exit the agreement.

The UN climate body requires one year’s notice for withdrawal, so the United States will not cease being a party for a year. Trump’s memo did not specify whether or not his administration will submit a formal notice of termination to the UN.