Today, half the prisoners in Guantanamo Bay are from Yemen, and the last two al Qaeda attacks against the U.S. mainland have originated there. While the United States has been busy with military engagements in Iraq and Afghanistan, this remote, lawless country has now emerged as the main staging area for attacks against the west.
Wracked with internal strife and political instability, Yemen is presenting a complicated challenge for U.S. policymakers, with no easy fixes and few good options.
Extra: U.S. Intervention in Yemen
Extra: Who Is Sheik Zindani
Yemen is one of the oldest civilizations in the Middle East, with 3,000 years of history. It is believed that Noah and the Queen of Sheba once lived there, and if they were to come back today they would find much of the countryside unchanged, except for the weapons.
It is a country of 23 million people and at least 23 million guns, many of them currently in use. Yemen's beleaguered government has been fighting a tribal war in the north, an armed secessionist movement in the south, and a growing insurgency from al Qaeda in the Arabian Peninsula. It is now the most active branch of the al Qaeda network.
"In many ways they are the most pressing threat against the U.S. homeland," former U.S. Ambassador Edmund Hull told correspondent Steve Kroft.
Few Americans know more about Yemen than Hull, who served there in the years immediately following 9/11.
Asked if he has any idea how many people in Yemen are affiliated with al Qaeda, Hull told Kroft, "You have a relatively small number of kind of hardcore inner circle in the hundreds, then you have a next circle, probably in the thousands of people who can be relied on to help out in a pinch. And then, a larger circle yet of people who are ideologically sympathetic to the organization."
Despite relatively small numbers, they have made their presence felt far beyond Yemen. The failed suicide bombing of this jetliner in Detroit a year ago Christmas was carried out by Umar Abdulmutallab, the Nigerian student was trained and equipped in Yemen with explosives sewn into his underwear.
And then there were the two Chicago-bound bombs that were supposed to blow up UPS and FedEx planes last October. They too originated in Yemen. The highly sophisticated devices were concealed in printer cartridges and believed to be the handiwork of Ibrahim al-Asiri.
"Al-Asiri is the bomb maker. He's apparently a very creative type who is adept at seeing chinks in our armor and challenging them," Hull explained.
In many ways Yemen is the perfect safe haven for al Qaeda.
There is a strong fraternity here of former jihadists who fought the Russians in Afghanistan. There are the porous borders and ports that make it easy to smuggle people in and out, and hundreds of thousands of square miles of desert and mountains where they can hide, train and plan their missions with the acquiescence of local tribes, and little interference from the government, which has limited presence outside the major cities.
And finally there is the grinding poverty and political discontent that al Qaeda seems to be exploiting: Yemen is the poorest country in the Arab world, there is a critical shortage of water, a third of its people are hungry, and resentment is building against the longtime autocratic President Ali Abdullah Saleh.