Yemen's own chronic problems are a major potential threat to order in the Horn of Africa
Somali pirates preying on shipping in the Gulf of Aden have struck most often off the coast of Yemen, an unstable, impoverished Arab state that has few resources to tackle the maritime scourge.
Ships often take sea lanes near Yemen to avoid proximity to pirate lairs in lawless Somalia or its breakaway Somaliland and Puntland regions, but there is no sign of Yemeni involvement in the attacks, diplomats in Sanaa and some analysts say.
They do not exclude links between Somali pirates and some of the several hundred thousand Somali refugees and migrants in Yemen, but cannot confirm theories that pirates have forged ties with criminal networks there during years of people-smuggling.
Many analysts, however, regard Yemen's own chronic problems as a major potential threat to order in the Horn of Africa.
"Future instability in Yemen could expand a lawless zone stretching from northern Kenya, through Somalia and the Gulf of Aden, to Saudi Arabia," concluded researcher Ginny Hill in a paper issued by London's Chatham House think-tank on Wednesday.
A European diplomat in Sanaa said the Yemeni government had grave concerns about maritime insecurity, in part because of the risk that it could damage efforts to attract foreign investment.
These include offshore oil exploration and a liquefied natural gas terminal due to operate next year, both seen as vital to counter declining oil output. Oil now accounts for 90 percent of export earnings and 75 percent of state revenue.
Despite Western training and assistance, Yemen's tiny coastguard and navy is ill-equipped to patrol its 1,906 km (1,191 mile) coastline, even against the crammed boatloads of Somali refugees smuggled to its shores every year.
"At the last count, the Yemeni navy had 15 ships, nine of which were operational. Only two have deepwater capacity," said another Sanaa-based diplomat. "Yemen lacks the ability to really police the deep water in the Gulf of Aden area."
Pirates operating across ocean expanses have defied the foreign navies trying to stop them -- they showed their reach last week by seizing a Saudi supertanker with a $100 million oil cargo 450 nautical miles southeast of Mombasa, Kenya.
A naval force with NATO and European Union components guards a shipping corridor in the Gulf of Aden. U.S., French and Russian warships are also deployed off Somalia.
Somali Prime Minister Nur Hassan Hussein told on Wednesday naval patrols alone could not stamp out pirates whom he linked to unidentified "criminal networks" beyond Somalia.
Such networks operate out of the United Arab Emirates, not Yemen, said Michael Weinstein, a Somalia expert and professor of political science at Purdue University in the United States.
"The major business interests abetting and controlling the piracy to a great extent are based in the UAE," Weinstein said, describing them as diaspora Somali entrepreneurs without known links to political or militant Islamist groups.