“With this seizure, we have significantly disrupted that cycle,” said Geoffrey S. Berman, the United States attorney in Manhattan.
North Korea’s economy can absorb the loss of a single ship and its cargo, said David Maxwell, a retired United States Army Special Forces colonel who is now a senior fellow at the Foundation for Defense of Democracies. “The bigger issue,” he said, “is the timing of this and the message it sends to Kim Jong-un that we can track your shipping and we can seize it under international law, and so we can put even more pressure on you.”
Mr. Demers also noted that the seizure was not just about one ship and one shipment. The Wise Honest is the second-largest cargo ship in Pyongyang’s fleet, he said, and the value of the ship is multiplied every time the North Koreans make shipments on it and evade sanctions.
While prosecuting foreign nationals who violate sanctions can be difficult and drawn out, “to actually seize and forfeit a significant asset of the country or the sanctions violator can provide a much more substantial deterrent,” said Sharon Cohen Levin, a former chief of the asset forfeiture unit of the United States attorney’s office in Manhattan.
The Justice Department seized the vessel from the Indonesians, and the United States Coast Guard evaluated it to ensure it was safe enough to make the trip, a spokeswoman said. The vessel is being towed by a commercial tow boat to American Samoa, officials said.
The United Nations Security Council has imposed five rounds of sanctions against North Korea since early 2016, when Pyongyang conducted its fourth nuclear test. China and others argued at the time that the sanctions would disproportionately affect ordinary North Koreans and could backfire.
In March, there were reports that the American-led sanctions on exports were indeed causing economic dysfunction by depriving North Korea of its main source of income.
When Mr. Trump and Mr. Kim met in Vietnam in February, Mr. Kim wanted the United States to lift the sanctions that were directly affecting the nation’s civilian economy. The meeting ended without an agreement.