Toughest Military training in the world?

I have seen many doentaries on military and they all seem really tough. Especially when it comes to special ops/ forces. I have read up on SEAL, MARSOC, SAS, SBS, ect but I just read a book called Kill Bin Laden Delta Force according to the book put on 60lbs and run up to 40 miles a day every day for a month! 3 out of 100 men make it! I was wondering if there is anything tougher than that.