"We’re not looking for regime change. I just want to make that clear. We’re looking for no nuclear weapons. … I’m not looking to hurt Iran at all," said the US president during a joint press conference with Japan's prime minister in Tokyo May 27. Donald Trump expressed some confidence that a deal with Iran with "tremendous economic potential" was possible.

The comments marked a significant shift in tone from a president whose administration has gone to great lengths to pressure the Islamic Republic, particularly in the past few weeks and most recently in the form of US reinforcements in the Persian Gulf.

Trump's conciliatory remarks were followed by reports that he had embraced a Japanese offer for mediation between Washington and Tehran. Japan's Prime Minister Shinzo Abe announced that his country would do "whatever it can" to alleviate "tension surrounding Iran" and avoid an "armed conflict."

In reaction, Iran's Foreign Ministry spokesman said there was "no prospect for negotiations with the United States for now," but confirmed that arrangements were being made for an upcoming visit to Tehran by the Japanese prime minister.