During an economic discussion between President Trump and the Japanese prime minister in June, Trump raised Japan’s attack on Pearl Harbor in an attempt to negotiate a bilateral trade deal complimentary to the U.S.

“I remember Pearl Harbor,” Trump told Prime Minister Shinzo Abe, according to The Washington Post, referencing the surprise attack, which launched the U.S. into World War II. The U.S. eventually launched its first and only nuclear weapons bombing in history against Japan.

Abe was enraged by the meeting with Trump, an incident the Post called reflective of the two’s relationship; a bond that was once close, but has become increasingly strained.

The main sources of contention between the two world leaders stem from Trump’s approach to negotiating denuclearization with North Korea and the President’s view on Japan’s trade practices.

Those divisions are creating an obvious rift. In July, Japan held a secret meeting with North Korea to discuss the return of Japanese citizens abducted by North Korea. While the U.S. was frustrated that Japan concealed the meeting, Tokyo officials told the Post that they couldn’t rely solely on the Trump administration to negotiate for them.

Despite the growing rift between the two leaders — whose friendship was strengthened through their shared loved of hitting the links — Abe doesn’t regret gambling on a strong relationship with Trump because without the personal bond, relations would be much worse, officials told the Post.

Read the Post’s full report here.