President Trump's team released details of how North Korean smuggling networks run through China and Russia, as part of a public campaign to tighten international pressure on the regime.

The information, typically tightly-guarded, was obtained by U.S. intelligence officials and provided to Congress through the Treasury Department. The public display of images tracking coal-smuggling ships builds a case that Russia and China are undermining international pressure campaigns, despite voting for the sanctions packages at the United Nations Security Council.

"North Korea is using deceptive practices to mask the origin of exported coal to Russia and China," Marshall Billingslea, the Treasury Department's assistant secretary for terrorist financing, told the House Foreign Affairs Committee in testimony prepared for a Tuesday hearing.

"In the first example, the ship travels from China and declares that it is traveling to Russia. During its journey, the ship turns off its automatic identification system (AIS), probably stops in North Korea to load coal, travels to Vladivostok, Russia, and then returns to China probably to offload the coal."

Coal is a major source of revenue for North Korea, which uses the money to finance the development of nuclear weapons and intercontinental ballistic missiles. The U.N. passed aggressive sanctions targeting the coal industry last year, but China promptly signaled it might not implement them fully, citing humanitarian reasons. More recently, the Chinese have increased trade in other sectors that mitigated the economic pain caused by the coal crackdown.

Secretary of State Rex Tillerson has been negotiating to improve Chinese cooperation, while warning the United States will impose additional sanctions on Chinese companies if they don't cut back the business.

"Their cooperation I would say has been notable, but it has been uneven," Tillerson told lawmakers in June.

The Treasury Department targeted an array of Chinese and Russian entities for sanctions last month due to North Korea ties. Billingslea praised them for backing recent U.N. sanctions, but suggested the governments haven't been serious about implementing such measures.

"[North Korean] bank representatives operate in Russia in flagrant disregard of the very resolutions adopted by Russia at the UN," he said. "China is even more central to a successful resolution of the crisis caused by Kim Jong-Un. ... Unfortunately, I cannot assure the committee today that we have seen sufficient evidence of China's willingness to truly shut down North Korean revenue flows, expunge the North Korean illicit actors from its banking system, and expel the North Korean middlemen and brokers who are establishing webs of front companies."

Billingslea suggested this lack of cooperation might lead to more sanctions on larger Chinese companies, a proposal committee chairman Ed Royce endorsed.

"We can designate Chinese banks and companies unilaterally, giving them a choice between doing business with North Korea or the United States," the California Republican said.