Last week, the Sunrise 689, a Vietnamese oil tanker, disappeared off the radar. This Thursday, it motored toward the Vietnamese coast under protection of a naval vessel. Pirates of unknown nationality had seized the ship Oct. 2 and kept its crew hostage while they siphoned a third of its cargo: some 2,000 metric tons of oil. "They put knives on our throats and threatened to kill us if we resist," the ship's deputy captain told the Associated Press by cellphone. One crew member broke his leg after trying to flee the pirates, reported the AP.

Luckily, there were no fatalities. The pirates jumped ship with their stolen booty and the tanker had to enlist the help of a passing fishing vessel to figure out its location and call for help.

The incident marked the latest pirate attack near the Malacca Strait, a body of water that links the Indian Ocean and the South China Sea, making it perhaps the world's most vital conduit for global shipping. It carries some 40 percent of world trade through its waters every year. The lands flanking these waters have been contested by local kingdoms and sultanates, Arabs, Chinese, and the forces of European colonial powers. Singapore, one of the world's most important ports, emerged in the 19th century as a pivotal entrepot straddling this passage. It was also, in its early days, a haven for pirates.

The attack was the 12th such pirate hijacking attempt in Southeast Asia since April, raising concerns about an escalation in piracy in this strategic waterway. The rise has been conspicuous enough that it initially dominated the fevered speculation surrounding Malaysian Airlines flight 370, when it tragically disappeared earlier this year.

From a dip in 71 attacks reported in the Malacca Strait and adjacent South China Sea in 2009, numbers surged back to 161 reported attacks in 2013. This graph from German news site Deutsche Welle lays out the trend over the past two decades.

Half a decade ago, as the world fretted over the terrors of Somali piracy, strategists pointed to the relative success of counter-piracy measures in the Malacca Strait as a guide for how to deal with the threat of the Horn of Africa. In a 2011 report, the American Enterprise Institute, a D.C-based conservative think tank, hailed the success of the "Malaccan formula":

The Strait of Malacca between Indonesia, Malaysia, and Singapore offers some interesting solutions. The “formula” in the Strait of Malacca, as outlined by Lt. Commander Jamiola of the U.S. Navy, consists of state-sponsored naval forces, regional intelligence sharing, surface surveillance radars, an effective court system, and fighting the origins of piracy on land. It has proved extremely successful, with the number of pirate attacks in the region declining each year since 2003.

An international task force began patrolling the waters off Somalia's lengthy coastline along a similar model, forcing Somali pirate "motherships" further afield from their bases on shore. The number of pirate attacks dried up, with piracy off West Africa's coast now becoming a greater security concern.

Piracy monitors caution that the recent spike in attacks near the Malacca Strait involves many "low-level thefts," including raids and burglaries conducted at night when ships are at anchor in port. The growing trend does not necessarily mean there's a greater deterioration and pirate threat in the region. This year alone, the U.S. navy held military exercises with Singapore that focused in part on anti-piracy maneuvers.