Debt of Honor - Spoiler Alert!
In the aftermath of the US & former USSR’s drawdown of forces, including the complete elimination of nuclear weapons, Japan takes advantage of their weakened military condition to obtain a few nuclear weapons of their own and then they retake the Marianas and Guam with eyes on capturing Siberia for its oil. But first they purposely take steps, similar to the 2008 financial meltdown, to cripple our economic system. In the midst of all this the vice-president resigns because of his involvement in a sexual scandal.
At the end of the book, after the US recovers from both the economic & military threats, in large part thanks to Jack Ryan as National Security Advisor, he is about to be confirmed as vice president when a Japanese pilot flies a 747 half-filled with fuel into the House of Representatives where everyone is gathered for the confirmation and swearing in ceremony. Of course, the president is killed, and an unknown number of other members of congress, and Jack Ryan instantly becomes President of the US. End of story! (BTW, the book was published in 1995, before 9/11.)