The United States will use a major meeting of allies next week to discuss the idea of stopping and inspecting suspect ships bound for North Korea, a senior official said Thursday.
The United States and Canada are to host a meeting on the nuclear standoff with North Korea on Tuesday in Vancouver, bringing together friendly powers from around the world.
State Department director of policy planning Brian Hook said Secretary of State Rex Tillerson would be looking for help developing "practical mechanisms" to pressure Pyongyang.
"We will be discussing maritime interdiction," Hook said, raising the idea of an naval embargo to help enforce the already draconian UN sanctions on Kim Jong-Un's regime.
Some countries, even friends of the United States, may be concerned that such methods could increase military tensions or be interpreted as an act of war by Kim's isolated regime.
But he said the idea was one of many being explored, and that the allies invited to Vancouver would be consulted.
"We will be discussing with our partners and allies the kind of steps that we can take on maritime interdiction and also to be cutting, disrupting funding and disrupting resources," Hook said.
"And maritime interdiction helps us to disrupt resources."
The countries invited to send representatives to Vancouver are the so-called "Sending Powers," those that contributed troops or aid to the UN war effort in 1950s Korea.
As such, North Korea's neighbors China and Russia are not invited, and many have questioned the utility of a conference where such influential regional players are absent.
But Hook said Washington remained in contact with China about enforcing the sanctions and pressuring Kim, and that both Beijing and Moscow would be briefed after the talks.
"China is working with us," he said. "This is not an alternative to everything that we are doing. This ministerial will enhance and strengthen all of the efforts under way.
"China has the same policy goal, in terms of ensuring that North Korea does not become a nuclear weapon state and acquire the means to deliver a nuclear warhead."