After 9/11 I began to suspect Bush made a deal with the Mexican drug lords somewhat similar to the deal FDR made with the Mafia during WWII.
During WWII FDR made a deal with the Mafia to protect the docks from sabotage. It worked. Once the Mafia had control of the docks, sabotage stopped.
After 9/11 I think Bush made a deal with the Mexican drug lords to keep terrorist from coming up through the southern border, in exchange Bush wouldn't seal the border.
I think that is the opening they found and they used it.
I might be wrong, but this appears to be just like the dope running into Mena with Iran-Contra. They couldn't stop the dope running without exposing Iran-Contra, they couldn't stop this without exposing the deal Bush made with the drug lords. If it is exposed it's all on Bush.