The UN Security Council this week added new sanctions against North Korea after leader Kim Jong Un's regime conducted its sixth and most powerful nuclear test. Mnuchin echoed the USA envoy to the UN, Nikki Haley, in calling the sanctions "historic", even though they didn't include United States demands for a full oil embargo and a freeze on Kim's assets.
"The premise is problematic, as China has executed all United Nations sanctions on North Korea", said He Weiwen, a senior fellow at the Centre for China and Globalisation in Beijing and a former official at the Ministry of Commerce, calling Mnuchin's remarks "pure bluff".
Frustrated U.S. lawmakers called on Tuesday for a high-powered response to North Korea's nuclear tests, saying Washington should act alone if necessary to stiffen sanctions on companies from China, Russia and any country doing business with Pyongyang.
"These are by far the strongest measures ever imposed on North Korea. but we all know these steps only work if all nations implement them completely and aggressively", Nikki Haley, the USA ambassador to the United Nations, said after the vote. It came just one month after the Security Council chose to ban exports of coal, lead and seafood in response to North Korea's launch of an intercontinental ballistic missile in late July that experts believe puts a large chunk of the United States - including Chicago and Los Angeles - within range of Pyongyang's ever-improving weapons systems.
Trump is said to plan a visit to China in November. The sanctions also cap refined petroleum imports at 2 million barrels per year, about a ten percent cut.
Those demands were toned down in negotiations that followed with her Russian and Chinese counterparts.
The US and its allies argue that tougher sanctions will pile pressure on North Korea to negotiate an end to its weapons programmes but experts are sceptical.
The Security Council vote comes just over a month after United Nations diplomats targeted about $1 billion in North Korean exports.
It was the eighth series of sanctions imposed on North Korea since it first tested a nuclear device in 2006. "In the medieval system like North Korea, Kim Jong-un's life is as valuable as hundreds of thousands of ordinary people whose lives would be threatened in a nuclear attack".
"North Korea economic warfare works", Mnuchin said.
In its statement Wednesday, North Korea's Foreign Ministry ripped into the sanctions, labeling them a "heinous provocation" led by the United States.
The resolution also calls on states to inspect vessels on the high seas, with consent of the flag state, if they have reasonable grounds to believe the ships are carrying prohibited cargo.
The latest measures, while watered down, are significant.