to let him know he was still open to denuclearization. Trump opened the letter and found a single-line coded message:
370HSSV - 0773H
Trump was confused, so he asked his aides to figure it out. The aides couldn't understand where the code came from, so they forwarded it to the FBI.
The FBI came back without an answer so they forwarded it to the CIA. The CIA had no idea so they reached out to the MSS (Ministry of State Security in China) for help.
Within a few seconds, MSS wrote back with this reply:
"Tell the President he's holding the message upside down."