Until recently, Somali piracy followed a simple script: Pirates attack and crews either successfully speed away or are taken hostage and must buy their freedom. That changed in April when Navy SEAL snipers killed three pirates to free Capt. Richard Phillips of the Maersk Alabama.

Since then, some lawmakers have called for the U.S. to step up its investment in anti-piracy efforts beyond the American warships already patrolling Somali coastal waters.

Enter Amendment No. 24 -- part of the $550 billion National Defense Authorization Act -- which would require the Defense Department to put small teams of four or five Marines on American-flagged ships carrying U.S. cargoes. The House approved the bill June 25, while the Senate has yet to move on it.

Ship owners, many of whom have been paying insurance premiums of $40,000 to $60,000 per transit through Somali waters, are ecstatic.

"This bill recognizes that there is an inherent need for the U.S. government to protect American-flagged ships in the region," said Philip Shapiro, president and CEO of New York-based Liberty Maritime Corp., whose ship the Liberty Sun was attacked April 14 but managed to escape.

"There is no doubt in our minds that putting armed soldiers on board is a highly effective solution and it will definitely prevent hijacking of the vessel," said Per Gullestrup, CEO of Copenhagen-based Clipper Projects, who negotiated the release of his ship CEC Future and its 13 crew members after pirates captured it last fall. None of his ships stand to benefit from the legislation, but Gullestrup has been an advocate for stepped-up international military assistance.

The legislation won't cover every ship sailing through the Gulf of Aden or off Somalia's Eastern coast that flies the Stars and Stripes. In a given year, 54 American-flagged ships travel the region, 40 of which carry humanitarian aid cargo from the federal government. But of those, fewer than 10 are small enough or slow enough to be at risk of attack and require Marine embeds, according to the U.S. Maritime Administration.

Some observers are balking nonetheless at what they see as a further misallocation of scarce naval resources, given that the American ships taking part in Combined Task Force 151 off the Somali coast already cost the Navy millions of dollars a week to operate. Meanwhile, just 1 out of every 70 to 80 ships transiting the pirate-infested waters flies an American flag, and the Alabama and the Sun are the only ones to have been attacked.

"I think, realistically, the Navy realizes that in the fiscal climate we're in, they operate under lots of constrictions," said J. Peter Pham, the director of the Nelson Institute for International and Public Affairs at James Madison University. "There are lots of demands on their services, and while piracy is a major problem, it's not a major problem affecting the U.S. It just so happens that the pirates were stupid enough to seize the Maersk Alabama, but we don't have many American-flagged ships."

Vice Adm. James A. Winnefeld testified at a Senate Armed Services Committee hearing in May that expanding naval operations in the Gulf of Aden would put a "large dent" in the Navy's operational capacity and detract from counterterrorism operations and the wars in Iraq and Afghanistan.

Shapiro bristled at the argument that because piracy has only touched a few American ships, it shouldn't command more naval resources.

"I would say that you should talk to our crew members: They took four RPGs and 1,000 rounds of AK-47 fire, and they didn't think it was a joke at all," he said.

But Pham argued that the U.S. could largely dodge piracy if the government purchased grain in East Africa instead of shipping food from the U.S. But shipping and agricultural interests have successfully blocked a policy shift toward sending local grain overland. Liberty Maritime has spent $229,000 on lobbying so far this year and the industry has a whole over $6 million, according to the Center for Responsive Politics.

"There wouldn't be the Maersk Alabama and others if we didn't buy grain in the U.S. and chug it halfway across the world," Pham said. "If that grain was purchased locally in Africa, there wouldn't be this shipping issue."