U.S. President Donald Trump says he’s ready to ease sanctions on Syria. He won’t be able to do it quickly.

The American leader sat down with Syrian counterpart Ahmed Al-Sharaa in Riyadh on Wednesday — the first meeting between heads of the two countries in 25 years — after unexpectedly saying he would drop all sanctions against the war-ravaged country and even look to normalize relations.

The move was seen as a highlight of Trump’s trip to the Arabian Peninsula this week, but actual implementation will be a protracted and thorny challenge. The White House also made clear it’s not a one-way street, saying the president urged Sharaa to take steps in return, including helping to fight terrorism and agreeing ties with Israel.