On Sept. 26 in New York, Prime Minister Shinzo Abe was facing reporters at a joint news conference with U.S. President Donald Trump when Trump cracked a joke that in fact sounded like a veiled threat.

"We've agreed today to start trade negotiations between the United States and Japan," Trump proudly said after a 75-minute meeting with Abe on the sidelines of the United Nations General Assembly.

"Japan was unwilling to do, and now they are willing to do so. We're very happy about that, and I'm sure that we'll come to a satisfactory conclusion. And if we don't, oh ...," Trump said, looking into Abe's eyes.