China’s growing sea power and the small number of U.S. merchant ships threaten U.S. economic and military security, a new report concludes.

China has “the ability to control — or even halt — shipping of essential goods by other nations. Nearly 30 percent of global trade currently passes through the South China Sea,” said the authors of “Sea Strangulation: How the United States has become vulnerable to Chinese maritime coercion.”

The authors, Hawaii Pacific University professors Patrick Bratton and Capt. Carl Schuster, said the best way to counter the threat is to “strengthen — and if possible expand — the U.S. Merchant Marine” by beefing up the Maritime Security Program and maintaining the Jones Act.

The U.S.-flag fleet includes about 80 ships engaged in foreign trade and 85-90 in domestic trade. The pool of mariners qualified for oceangoing service is 11,000 to 12,000. They are far outnumbered by the Chinese-flag merchant fleet in global trade, which counts 3,941 bluewater vessels, another 3,000 in coastal work, and 500,000 commercial mariners.

“America’s weakness in commercial shipping could become our Achilles’ heel,” if war were to break out with China or others, who could blockade supplies for U.S. forces, the report said. What’s more, “China does not need to blockade foreign ports to cut off the flow of goods: it will soon have the ability to control U.S. foreign trade” by manipulating shipping rates or ocean carrier service, the authors wrote. “The mere threat would disrupt global financial markets.”

The Jones Act, which requires cargo moved between U.S. ports be on vessels that are U.S. built, owned and crewed, is critical to the nation’s security. Opening U.S. coastal waters to foreign vessels would be dangerous, the study says. Attacks since 9/11 “would pale in comparison to the impact of a jihadist-controlled vessel entering a major U.S. riparian port with a thousand tons or more of explosives, flammable liquids, or toxic materials.”

The act has come under attack on a number of fronts, including the higher cost of U.S. construction and cost of goods shipped to Hawaii and Puerto Rico, but supporters have beat back attempts to change it.

“It is hard to believe that our maritime capabilities are shrinking to those comparable during the time of the Spanish-American War, when the U.S. government had to charter foreign-flagged vessels to bring coal to the ships of the Great White Fleet,” Don Marcus, president of the International Organization of Masters, Mates & Pilots (MM&P), said in the report. “Does anyone really believe that the world has evolved into a friendlier place where we can now entrust our security to foreign shipping interests?”

“We need to think about the maritime industry holistically, which is why I’m an advocate of the Jones Act,” said Capt. Schuster, who’s retired from the U.S. Navy. “The majority of the cost of a ship is its lifetime cycle cost. Construction is one factor over its 30-year life.

“In Desert Storm, Russia and China were on our side,” he said. “Can we take that for granted in the future? No.”

Read the full report.