DUBAI // A US maritime agency has warned of an increased risk of attacks by extremist groups in the Arabian Sea.
The US Maritime Administration (Marad) issued a guidance on March 13 saying "elevated regional tensions have increased the risk of potential maritime attacks conducted by extremists".
The warning came with advice for vessels in the Gulf of Oman, the north Arabian Sea, the Gulf of Aden and the Bab el Mandeb, the strait between Arabia and Africa.
It recommends that "vessels at anchor, operating in restricted manoeuvring environments or at slow speeds be especially vigilant and report suspicious activity".
Pottengal Mukundan, director of the International Maritime Bureau, said shippers should pay heed.
"There is usually background intelligence behind such advisories and it should be taken seriously by the vessels affected," Mr Mukundan said.
Maritime vigilance has always been crucial off the UAE because of its proximity to the Strait of Hormuz, through which a fifth of the world's oil exports passes.
And there are recurring threats by Iran to block the strait, and concerns about mines and terrorist strikes on offshore oil installations.
Security companies said ships were most vulnerable when at anchor and while travelling through narrows such as the strait.
"If it's a vigilante group they could sail between fishing boats and skiffs before breaking out, so it's a question of being alert," said Rhynhardt Berrange, head of Global Maritime Security Solutions in Dubai that supplied the guards on MV Arrilah-I.
The UAE bulk oil carrier was attacked by Somali pirates in 2011 and freed after a raid by UAE Special Forces and the US Fifth Fleet.
"My advice is don't step down the vigilance," Mr Berrange said. "The risk areas where ships must be alert is at anchor off Yemen, Salalah, Fujairah, Doha, Muscat, Aden and Djibouti.
"An incoming vessel usually does not have security so once security crews leave, the ships are soft targets until embarkation."
Constant monitoring is necessary to deters attacks for big ships, which are more vulnerable because they are not as manoeuvrable.
"A vigilante group would strike with a boat full of explosives, and a tanker at 10 knots cannot get away from a fast speedboat," Mr Berrange said.
Experts said the history of such attacks in the region include the Al Qaeda bombing of the USS Cole in 2000 at Yemen's Aden port; the 2002 attack on the MT Limburg in the Gulf of Aden; and the unsuccessful attack on the M Star tanker in the Strait of Hormuz in 2010.
Ian Millen, Dryad Maritime's director of intelligence, said there could be many threats.
"International terrorist groups are many and varied, from Al Qaeda affiliates to individual national groups and factions," Mr Millen said. "All are potential perpetrators of maritime terrorism.
"The volatile political situation in the Middle East is capable of spawning a wide range of terrorist groups."
He said the consequences of an attack would be wide-ranging.
"Concerns regarding the environmental and economic impact of attacks on tanker shipping are well founded," Mr Millen said.
"The consequences of a successful attack would be felt across the region and beyond, potentially affecting regional and global economies alike. There would also be an impact on the confidence of the shipping industry."
Cooperation was urged by Steven Jones, maritime director of the regulatory body the Security Association for the Maritime Industry.
"When advice is given it is vital that it generates a response," Mr Jones said. "The fact that Marad believes there is a threat should, and will be taken seriously by shipping companies.
"All too often there is too much emphasis on what seafarers, ships and shipping should do to protect itself.
"They should be supported and bolstered by parallel actions taken by flag, port and coastal states. Only by working in tandem can serious security threats be tackled."