But ever since North and South Yemen united in 1990, the central government in Sanaa has been slowly waking up to the island's potential.

ECONOMIST: An imperilled Arabian paradise

So there are few recent examples of mergers between nation-states (North and South Yemen and the two Germanies are rare exceptions) but many of secession.

ECONOMIST: How big should a nation-state be?

Under the agreed evacuation plan most of the PLO fighters will go to Cyprus and then be dispersed to Jordan, Syria, Iraq, Sudan, North and South Yemen, Tunisia and Greece.

BBC: 30 August

It has also crucially gone on offense, from Afghanistan to Iraq to Yemen and North Africa, keeping foreign terrorists on the run and making it harder to plot attacks on the U.S. homeland.

WSJ: Review & Outlook: Terror in Boston

Unnamed Saudi officials quoted in The New York Times describe al-Ghamdi as a militant cleric from the same tribe as several of the aircraft hijackers of September 11 -- a tribe from Saudi Arabia's Asir Province, north of the Saudi border with Yemen.

CNN: Sheik in bin Laden videotape may be Saudi cleric

The region extends from Egypt to Pakistan and covers countries as far north as Kazakhstan and as far south as Yemen.

CNN: Petraeus takes helm of U.S. Central Command

In other countries, such as Yemen, Somalia or portions of North Africa, the Defense Department will handle the drone strikes as regular military operations.

NPR: 4 Americans Killed Since 2009 In US Drone Strikes

Southern Yemen, a separate country before unification with the more populous north in 1991, has been increasingly racked by separatist unrest.

ECONOMIST: Yemen��s election

Correspondents say the security situation in Yemen is complicated by an abundance of firearms, an insurgency in the north and a secessionist movement in the south.

BBC: Yemen instability poses a 'global threat', says Clinton

The unrest in Yemen began in 2011 as the population got caught up in the Arab Spring uprisings that swept North Africa and the Middle East.

CNN: Former president demands foes leave Yemen