U.S. President Donald Trump has demanded that Japan pay $8 billion per year for costs associated with hosting American troops — or risk their withdrawal — former national security adviser John Bolton has alleged in his new memoir.

In the controversial book "The Room Where It Happened," obtained by The Japan Times before its scheduled release on Tuesday, Bolton said that he met with his Japanese counterpart at the time, Shotaro Yachi, in July last year to explain “why Trump wanted $8 billion annually,” starting from next year, “compared to the roughly $2.5 billion Japan now paid.”

The demand, the hawkish former top security official wrote, was part of a negotiating strategy he said Trump had termed “cost plus 50 percent” — the amount that the U.S. would seek from allies where it had troops stationed.