Iran-backed rebels of the Shiite Houthi sect sparked alarm in Washington after seizing a presidential palace in the volatile Sunni-majority nation, in what officials called a coup.

There are now signs that the rebels -- which have been resistant to American anti-terror efforts despite a common antipathy to al Qaeda -- and the U.S.-backed government of President Abdu Rabu Mansour Hadi have agreed a deal to end the crisis.

But the situation remains volatile and a reminder of how the intricate, shifting and treacherous tribal and sectarian divides of the Middle East often confound U.S. efforts to frame coherent anti-terror policy.

Obama has spent much of his administration sponsoring a political transition designed to restore stability in Yemen and to cap the sectarianism that sustains al Qaeda in the Arabian Peninsula (AQAP).

Washington has offered counter-terrorism training to the government in the Yemeni capital Sanaa and has also mounted a campaign of drone strikes against key AQAP leaders.

The group is regarded by U.S. officials as the most potent offspring of Osama bin Laden's jihadist movement and has claimed responsibility for the attack on the French satirical magazine Charlie Hebdo this month.

AQAP also almost succeeded in bringing down a United States commercial jet over Detroit on Christmas Day 2009, and has tried to attack the U.S. mainland on at least two other occasions.

The group's potential was underlined in a video released on Wednesday in which a senior leader of AQAP in Yemen, Nasser bin Ali al-Ansi, said it was better for jihadists to wage war in their home nations, rather than fighting on the front lines in Syria.

The message will alarm Western governments fearful that Muslim extremists radicalized at home or who have fought in Syria, Iraq or Yemen are plotting new attacks in the wake of the Paris carnage.