Washington/Beirut: In the midst of two unfinished major wars, the US has quietly opened a third, largely covert front against Al Qaeda in Yemen.

A year ago, the Central Intelligence Agency (CIA) sent some of its top field operatives with counter-terrorism experience to the country, according to a former top agency official. At the same time, some of the most secret special operations commandos have begun training Yemeni security forces in counter-terrorism tactics, senior military officers said.

The Pentagon, which is the headquarters of the US department of defence, is spending at least $70 million (Rs327.6 crore) over the next 18 months, and using teams of special forces personnel to train and equip Yemeni military, interior ministry and coast guard forces, more than doubling previous military aid levels.

As US investigators sought to corroborate the claims of a 23-year-old Nigerian man that Qaeda leaders in Yemen had trained and equipped him to blow up a Detroit-bound Northwest Airlines jet on Christmas Day, the plot casts a spotlight on the Obama administration’s complicated relationship with Yemen.

The country has long been a refuge for jihadis, in part because Yemen’s government welcomed returning Islamist fighters who had fought in Afghanistan during the 1980s. The Yemen port of Aden was the site of the audacious bombing of the US navy destroyer Cole in October 2000 by Qaeda militants, which killed 17 sailors.

But Qaeda militants have made much more focused efforts to build a base in Yemen in recent years, drawing recruits from throughout the region and mounting more frequent attacks on foreign embassies and other targets. The White House is seeking to nurture enduring ties with the government of President Ali Abdullah Saleh and prod him to fight the local Qaeda affiliate, Al Qaeda in the Arabian Peninsula, even while his impoverished country grapples with seemingly intractable internal turmoil. With fears also growing of a resurgent Islamist extremism in nearby Somalia and East Africa, administration officials and US law makers said Yemen could become Al Qaeda’s next operational and training hub, rivalling the lawless tribal areas of Pakistan, where the organization’s top leaders operate.

“Yemen now becomes one of the centres of that fight," said Joseph I. Lieberman, senator of Connecticut and chairman of the senate committee on homeland security and government affairs, who visited the country in August. “We have a growing presence there of special operations, green berets, intelligence," he said.

US and Yemeni officials said that a pivotal point in the relationship was reached in late summer after separate secret visits to Yemen by General David H. Petraeus, the US regional commander, and John O. Brennan, President Barack Obama’s counter-terrorism adviser.

Saleh agreed to expanded overt and covert assistance in response to growing pressure from the US and Yemen’s neighbours, notably Saudi Arabia, from which many Qaeda operatives had fled to Yemen, as well as a rising threat against the country’s political inner circle, the officials said.

“Yemen’s security problems won’t just stay in Yemen," said Christopher Boucek, who studies Yemen as an associate at the Carnegie Endowment for International Peace in Washington. “They’re regional problems, and they affect Western interests."