The eight black-helmeted Coast Guard "force protection team" members snaked their way through the big replenishment ship, rifles covering their movement, before detecting what they were looking for: simulated radiological material.
One had a portable diamond blade circular saw on his back used for cutting doorway hinges.
Another had a pry bar among his gear.
"I'm getting a detection," shouted one team member.
The team also carries cellphonelike "pagers" that detect gamma and neutron radiation.
From there the Coast Guard team zeroed in on a shipping container with a device known as an "Identifier U" that confirmed what was simulated to be inside.
"I got a positive on the plutonium," said Petty Office 3rd Class Larry Provost, a maritime enforcement specialist.
The demonstration by the Maritime Safety and Security Team was the last of three ship boardings and searches conducted last week by the United States, South Korea and Japan aboard the replenishment oiler USNS Henry J. Kaiser about 12 miles south of Pearl Harbor.
The U.S. Pacific Command hosted the exercise, Fortune Guard 2014, over four days as the United States and fellow nations that endorse a Proliferation Security Initiative seek to prevent the development of weapons of mass destruction by rogue nations and terrorist groups.
Thirty-five nations were invited to attend. Eighteen showed up, officials said.
China was invited but chose not to attend.
Since 2003 and 11 initial endorsing nations, the Proliferation Security Initiative has grown to include 106 nations worldwide, said Lt. Cmdr. David Leather, chief planner for WMD plans and policy within the Pacific Command.
Fortune Guard represents the debut exercise in a new formalized rotation of annual training that was held first by the United States and then will be hosted by New Zealand, Australia, Singapore, South Korea and Japan.
"All of the countries have done this on their own, but as it becomes more formal and as it becomes more routine, we want to make sure that it is happening on an annual basis and that the drumbeat continues with the initiative," Leather said.
That effort is getting harder, not easier.
"The international community faces a serious challenge," the Carnegie Endowment for International Peace said in 2012. "Trade is globalized, technology is spreading rapidly, and demands for economic development and uninhibited exchange of goods are greater than ever."
Unfortunately, technology and materials relevant to weapons of mass destruction "are all around us," Carnegie said.
Semiconductors used in computers can be used in military equipment. Freeze-drying technology can be used in biological warfare applications.
"The broad applications for dual-use goods and technology in everyday life result in constant flows of proliferation-sensitive items across borders," Carnegie said. "And this poses a real danger."
About 45 ministry of defense and foreign affairs and customs representatives from more than a dozen countries watched the ship-boarding drills by the three countries.
Fortune Guard also included a tabletop exercise on national-level decision-making in interdiction scenarios. The search of an aircraft for smuggled radiological cargo also was planned.
The concern over WMDs also comes in an environment in which nuclear North Korea was deterred from shipping suspected missile technology to Myanmar in 2011, and a North Korea-bound ship was seized last year by Panama that was carrying two MiG jets, 15 MiG engines and nine anti-aircraft missiles hidden in a cargo of sugar.
For last week's exercise at sea, the Henry J. Kaiser was redesignated the "Purple Trader 5," coming from country "Blue" and headed to "Purple."
The South Korean boarding team arrived by two small boats from the destroyer Wang Geon, while the Japanese team came from the helicopter destroyer Ise on a single boat.
Both teams clambered up the side of the ship using a rope ladder.
The U.S. Coast Guard team started onboard the 678-foot Kaiser. Australians from the submarine Sheean role-played as members of the boarded ship's company.
Maritime Safety and Security Teams were created in response to the Sept. 11, 2001, terrorist attacks and provide waterborne and shoreside anti-terrorism force protection for strategic shipping, high-interest vessels and critical infrastructure, according to the Coast Guard.
The Honolulu team has approximately 70 members, said its commander, Cmdr. Paul Frantz. There are 11 of the teams in the Coast Guard.
The force protection element within the teams is a "little bit higher-end as far as their tactics and their capabilities," Frantz said.
But as the Coast Guard evolves again, the Honolulu force protection team in coming years is expected to be absorbed into a larger Maritime Security Response Team in San Diego with the ability to deploy into the region, Frantz said.
Honolulu will still have a boarding capability and ability to escort ships in and out, but "for the higher-end threats" would have to reach back to San Diego or a similar response team on the East Coast, Frantz said.
"(With) a team of eight individuals, it would be very challenging to actually conduct any type of threat boarding on a vessel this size," Frantz said of the Kaiser. "A vessel this size requires many more tactical operators than what you saw here, and those (East and West Coast) units would have those numbers to be able to support those type of threats."