The increased violence in Yemen is a clear indication that military campaigns to crush al-Qaeda-inspired violence extend far beyond the borders of Afghanistan and Pakistan.
It also shows up hostile fault-lines within the Middle East, pitting mainly Shia Iran against Sunni Saudi Arabia, who condemn each other for taking sides in Yemen's long-running civil war.
Yemen is one of the poorest countries in the Arab world with almost half its 24 million people living below the poverty line and an authoritarian government that has failed to win the trust of a substantive part of its own population.
This makes fertile ground for al-Qaeda.
US intelligence agencies have determined that, along with Pakistan, Yemen is a key area on which to concentrate on al-Qaeda.
More than 90 detainees still in America's Guantanamo Bay detention centre come from Yemen. That is nearly half the total.
Despite the policy to close Guantanamo, US authorities do not want to send them back for fear that they would boost al-Qaeda's operations and morale there.
The US has invested some $70m (£40m) in military aid in Yemen in the past year, believed to include training, the use of drones and intelligence to pinpoint al-Qaeda camps and activity.
Much is classified because neither Yemen nor the US wants American activities there to stir up yet more dissent.
The instability in Yemen is becoming critical. Al-Qaeda has announced that its networks in Yemen and Saudi Arabia have merged to create al-Qaeda in the Arabian Peninsula.
The civil war is being waged by the Shia community in the north that borders Saudi Arabia. Saudi forces have actively intervened.
In one case it was accused of bombing a market killing many civilians.
Iran has publicly warned against any foreign intervention.
And - although the phrase is now frowned upon - US intelligence agencies are keeping a closer and closer watch in this newly-emerging theatre in the "war on terror".
http://news.bbc.co.uk/1/hi/world/middle_east/8429843.stm
The Christmas Day plot to blow up Northwest Airlines Flight 253 in the skies over Detroit was hatched in an impoverished republic on the Arabian Peninsula, according to jihadist websites.
Suspected Nigerian plane bomber Umar Farouk Abdulmutallab told FBI investigators that he was trained in Yemen, where the CIA is running a "covert front" against al-Qaeda, according to the New York Times.
US military planners are growing increasingly concerned that Yemen could rival Iraq and Afghanistan as a security challenge, if they do not act pre-emptively to dismantle terrorist networks. YEMEN FACTS
Population: 23.6 million (UN, 2009)
Capital: Sanaa
Major language: Arabic
Major religion: Islam
Oil exports: $1.5bn/24.5m barrels (Jan-Oct 2009)
Income per capita: US $950 (World Bank, 2008)
Trainers from the US military have been discreetly working with Yemen's elite counter-terrorism unit for several years.
But during the past 12 months, concern that al-Qaeda could establish a new "safe haven" in the Arabian Peninsula has been rising. Now, the budget for US military assistance to Yemen is doubling.
Earlier this month, President Barack Obama allegedly gave his personal approval for the Yemeni authorities to launch a missile strike against an al-Qaeda camp, killing more than 30 people.
A second strike, a week later, was targeted at a gathering of militant leaders, supposedly backed by US intelligence.
But Yemenis are warning that direct US intervention will inflame anti-Americanism and encourage violent extremism in this observant Muslim country, just several hundred miles from Mecca - the holiest site of Islam.
Narrow escape
Yemen has become the new centre of gravity for al-Qaeda on the Arabian Peninsula, following the January 2009 merger of al-Qaeda in Yemen and al-Qaeda in Saudi Arabia to form a single transnational organisation.
In August, Saudi Arabia's deputy interior minister, Prince Muhammad bin Naif, narrowly escaped assassination when an al-Qaeda affiliate blew himself up at the prince's house. If the state fails, al-Qaeda is sure to gain a greater foothold in the poorest country in the Middle East
The bomber, a Saudi national, had planned and prepared the attack across the border in Yemen.
In an echo of the Northwest Airlines plot, the suicide bomber packed PETN (pentaerythritol) explosives inside his body to evade detection but failed to kill his intended target.
The botched attack highlighted the intention of al-Qaeda operatives in Yemen to strike outside the country's borders.
It also underlined the importance of Yemen's internal security to Saudi Arabia, the region's largest oil producer.
State failure
Yemen's terrorist networks have reconstituted themselves since a 2006 jailbreak, when more than 20 suspected and convicted terrorists escaped from prison.
Since then, Yemen has also paid the price for security gains elsewhere in the region.
Crackdowns in Saudi Arabia, Iraq and Pakistan have encouraged al-Qaeda associates to flee to Yemen's "under-governed" areas, where the central government confronts the prospect of state failure.
The Yemeni authorities are fighting a costly civil war in the north, with the help of Saudi Arabia, and confronting a separatist movement in the south.
Yemen's economy is heavily oil-dependent but production has passed its peak and revenue available to the state budget is likely to dwindle to zero over the coming decade.
If the state fails, al-Qaeda is sure to gain a greater foothold in the poorest country in the Middle East.
Ironically, Yemen's poverty has played a part in maintaining its reputation for piety, which draws hundreds of Muslims and converts from all over the world to pray and study in its mosques and madrassas.
Many are devout scholars, attracted by the hardline brand of Salafi Islam that prospers in Yemen.
But Mr Abdulmutallab's claim that other al-Qaeda operatives are being trained in Yemen will raise concerns about the process of radicalisation in this strategic, populous Arab country.
http://news.bbc.co.uk/1/hi/world/middle_east/8433519.stm