How did Khalid Sheikh Mohammed confess to bombing buildings before they were built?

* The February 1993 bombing of the World Trade Center in New York City
* A failed "shoe bomber" operation
* The October 2002 attack in Kuwait
* The nightclub bombing in Bali, Indonesia
* A plan for a "second wave" of attacks on major U.S. landmarks after the 9/11 attacks, including the Library Tower in Los Angeles, the Sears Tower in Chicago, the Plaza Bank Building in Seattle and the Empire State Building in New York
* Plots to attack oil tankers and U.S. naval ships in the Straits of Hormuz, the Straits of Gibraltar and in Singapore
* A plan to blow up the Panama Canal
* Plans to assassinate Jimmy Carter
* A plot to blow up suspension bridges in New York City
* A plan to destroy the Sears Tower in Chicago with burning fuel trucks
* Plans to "destroy" Heathrow Airport, Canary Wharf and Big Ben in London
* A planned attack on "many" nightclubs in Thailand
* A plot targeting the New York Stock Exchange and other U.S. financial targets
* A plan to destroy buildings in Eilat, Israel
* Plans to destroy U.S. embassies in Indonesia, Australia and Japan in 2002.
* Plots to destroy Israeli embassies in India, Azerbaijan, the Philippines and Australia
* Surveying and financing an attack on an Israeli El-Al flight from Bangkok
* Sending several "mujahideen" into Israel to survey "strategic targets" with the intention of attacking them
* The November 2002 suicide bombing of a hotel in Mombasa, Kenya
* The failed attempt to shoot down an Israeli passenger jet leaving Mombasa airport in Kenya
* Plans to attack U.S. targets in South Korea
* Providing financial support for a plan to attack U.S., British and Jewish targets in Turkey
* Surveillance of U.S. nuclear power plants in order to attack them
* A plot to attack NATO's headquarters in Europe
* Planning and surveillance in a 1995 plan (the "Bojinka Operation") to bomb 12 American passenger jets
* The planned assassination attempt against then-U.S. President Bill Clinton during a mid-1990s trip to the Philippines.
* "Shared responsibility" for a plot to kill Pope John Paul II
* Plans to assassinate Pakistani President Pervez Musharraf
* An attempt to attack a U.S. oil company in Sumatra, Indonesia, "owned by the Jewish former [U.S.] Secretary of State Henry Kissinger"
* The beheading of Wall Street Journal reporter Daniel Pearl







Answer :
there are 2 possible reasons:
He was tortured. During that people confess a lot of nonsense (flying on broomsticks for example)
He wanted to show off.