But just how far the US will go is unclear, and the move may be more political than militarily muscular.
The Obama administration has vowed to conduct inspections of North Korean vessels in the wake of that country's nuclear tests, acts seen as provocations by the US, China, Russia, and others in recent months.
The US and other countries will monitor ship traffic in and out of North Korea, looking for contraband that could be used in the creation of nuclear materials. The move comes after a UN Security Council resolution authorized it Friday.
The UN resolution authorized only voluntary inspections, meaning any vessel can choose not to comply with a request to inspect its cargo. Indeed, few expect any ships to agree to be inspected, regardless of what they are carrying.
"Those ships should be stopped and searched if there is probable cause," he wrote.
If a North Korean ship were to refuse inspection, that would force American ships to "steer" or follow the vessel in question into a nearby port, where the North Korean ship could face negative publicity that would draw attention to what it may or may not have aboard. The international community could also refuse to refuel those ships or deny other services the ship needs to continue.
What happens after that, however, is anyone's guess, and administration officials are mum for now. This spring, Pyongyang said it would retaliate if any ships are forcibly boarded, and the US is not keen to start a fight.
But the move is seen less as an attempt to actually inspect North Korean ships and more as a way to galvanize the international community to work together.
"An important element of this is information-sharing," says Nicholas Szechenyi, a fellow at the Center for Strategic and International Studies, a think tank in Washington. "In terms of information-sharing and intelligence gathering, I think it's very significant."
Mr. Szechenyi suggests that the result will be a unified front against North Korea's actions.
North Korea tested a ballistic missile device in April and then held an underground nuclear test May 25, followed by other rocket tests, all drawing international rebuke.
During a briefing Tuesday, Pentagon press secretary Geoff Morrell would not say what the US Navy's operational plans are or when the stepped-up monitoring would start. No new US ships would likely be needed in the region, he said.
Meanwhile, President Obama Tuesday reinforced the US alliance with the Republic of Korea, appearing with South Korean President Lee Myung-Bak in the Rose Garden of the White House to say the North has options: peace and prosperity.
"That destination can only be reached through peaceful negotiations that achieve the full and verifiable denuclearization of the Korean peninsula," Mr. Obama said.