A tip from the Saudi Arabian intelligence may be all that kept two homemade bombs, hidden in Hewlett-Packard printers, from detonating inside cargo planes in the United States.  That and a well-coordinated effort between government officials around the globe.

Two bombs, one sent via FedEx, one via UPS, were mailed to Chicago from Yemen Oct. 27. 

One made it to Dubai before being discovered by authorities, the other to England.  Once the Saudis tipped off the CIA about the existence of the bombs, a series of good contacts prevented a major disaster, the AP reported Saturday.

"Authorities believe it was the most sophisticated effort yet by al-Qaida in Yemen to strike inside the U.S.," the story reads. "The pursuit shows that even when the world's counterterrorism systems work, preventing an attack is often a terrifyingly close ordeal."

The bombs, believed to be made by al-Qaida's master bombmaker in Yemen, Ibrahim Hassan al-Asiri, were of high quality.  They were set to detonate according to cell phone alarms embedded into the devices.

Taking advantage of the fact that the U.S. relies on shipping companies like UPS and FedEx to screen packages until they arrive in America, al-Qaida focused on cargo packages.

The concept was not new to American intelligence, however.  The FBI had participated in an August drill tracking a homemade bomb shipped by cargo plane:

"U.S. authorities had been monitoring steady intelligence on a possible attack like this since early September, a U.S. official said. In early October, the U.S. received a general tip from the Saudis about a possible al-Qaida effort to down airplanes, intelligence officials said."

It's clear that without Saudi Arabia, the bombs would likely not have been found in time.  GlobalPost reports the country has built a very legitimate counterterrorism force in this decade:

“There’s been an incredible investment of U.S. time and expertise in helping the Saudis develop their intelligence capabilities,” said Jarret Brachman, author of “Global Jihadism: Theory and Practice.” “They’ve really come a long way ... and have developed an independent capability … that’s moved much more into human intelligence collection.”

In October, the Obama Administration announced a $60 billion arms deal with Saudi Arabia, signalling the rebirth of a key alliance that had broken down after 9/11.

The Saudis were forced to reevaluate their stance on religious extremism after 15 of the 19 9/11 hijackers turned out to be Saudi Arabian, Robert Lacey argues in The Daily Beast.

There is some room for optimism after successfully blocking Yemen's al-Qaida this time.  But the evidence points to future efforts by that group, and to an improved system still only as good as human.