The U.S. tightened its financial restrictions on North Korea, slapping sanctions on Chinese and Russian entities it accused of assisting Pyongyang's development of nuclear weapons and ballistic missile. It's also seeking millions of dollars it said moved through the U.S. as part of the alleged scheme.

Prosecutors in Washington , D.C ., are seeking to recover $11 million from companies based in China and Singapore that they accuse of conspiring with North Korea to sidestep sanctions. In grievances filed Tuesday in a federal tribunal in the District of Columbia, they said the companies laundered dollars through U.S. accounts on behalf of sanctioned entities in North Korea.

The sanctions and forfeiture petitions are the latest against third-country companies and individuals in an effort to exert greater economic pressure on Kim Jong Un's regime, which has conducted regular weapon and nuclear tests in defiance of United Nations resolutions and has developed weapons that may be capable of making the continental U.S. President Donald Trump has sought to pressure China — North Korea's top trading partner — to use greater leverage on its neighbor and ally, though Kim's regime often constructs decisions contrary to Beijing's wishes.

” These grievances depict our determination to stop Northern korean sanctioned banks and their foreign fiscal facilitators from aiding North Korea in illegally accessing the United States financial system to procure goods and services in the global market place ,” said U.S. Attorney Channing D. Phillips.” According to the complaints, these front companies are supporting sanctioned North Korean entities, including Northern korean military and Northern korean weapons programs .”

Blacklisted Entities

Earlier Tuesday, the U.S. Treasury added more than a dozen individuals and companies to its roster of blacklisted North Korea-related entities, an escalation of the Justice Department's focus on tightening sanctions against Pyongyang.

Treasury's Office of Foreign Assets Control added six private individuals and 10 companies and other entities to its sanctions listing, saying they have helped people previously penalise for North Korea's weapons program, facilitated North Korea's energy sector and enabled entities to bypass sanctions to get access to the U.S. and international financial system.

The new limiteds seek to further reduce the flow of fund to North Korea's weapons development, which is partially was funded by selling coal and other natural resources. North Korea generates about$ 1 billion a year from the coal trade, according to the Treasury, which singled out three Chinese coal companies it said is in charge of importing almost a half-billion dollars in North Korean coal between 2013 and 2016.

” Treasury will continue to exert pressure on North Korea by targeting those who support the advancement of nuclear and ballistic missile those programmes and isolating them from the American financial system ,” Treasury Secretary Steven Mnuchin said in a statement accompanying the sanctions announcement.

Read a QuickTake on North Korea's nuclear weapons program

As part of the announcement, three Russian individuals and two Singapore-based companies were accused of petroleum to North Korea.

The sanctions described the ire of Russia, which already is at odd with the U.S. over its annexation of Crimea and interference in the American presidential election. Deputy foreign minister Sergei Ryabkov said in a statement on the ministry's website that international sanctions against the Russian individuals continues a trend damaging the U.S.-Russia relationship. He warned that Russia would develop unspecified” counter-measures inevitable in this situation .”

In early July, after tensions with Pyongyang escalated, U.S. attorneys disclosed their effort to seize millions of dollars linked to North Korean entities from eight global banks.

In lawsuits filed Tuesday in Washington, attorneys outline how a web of front companies — some run by Russian nationals — were used by North Korean banks, including the country's government-owned Foreign Trade Bank, or FTB, to launder fund through transactions involving coal and oil.

In one of the lawsuits, U.S. attorneys allege that Singapore-based Velmur Management Pte. Ltd and Transatlantic Partners Pte. Ltd. laundered U.S. dollars for sanctioned Northern korean banks that were seeking to buy petroleum products from JSC Independent Petroleum Company, a blacklisted entity are stationed in Russia.

Velmur Payments

North Korean banks utilized companies such as Transatlantic to stimulate U.S. dollar payments to Velmur, according to the complaint. The suit involves monies that the U.S. alleges were transferred through four companies to Velmur, which then wired the proceeds to JSC. That company was designated a sanctioned entity by OFAC on June 1 for allegedly shipping more than$ 1 million of petroleum products to North Korea.

The U.S. is attempting the$ 7 million that was wired to Velmur in May.

In a second lawsuit, China-based Dandong Chengtai Trading Limited and related companies are accused of laundering millions of dollars for North Korea through the acquisition of coal. Dandong Chengtai was added Tuesday to Treasury's list of sanctioned entities, along with Transatlantic and Velmur. It wasn't immediately possible to situate company representatives for comment.

Controlled by Chinese national Chi Yupeng, Dandong Chengtai allegedly conspired to evade U.S. sanctions by facilitating proscribed U.S. dollar transactions on behalf of the Northern korean Workers' Party, a sanctioned entity, according to the complaint.

Dandong Chengtai allegedly made U.S. dollar wire transfers for purchases of goods that are well outside the scope of a mineral trading company and financial records allegedly show that buys of bulk commodities such as sugar, rubber, petroleum products and soybean petroleum , among others, were in fact destined for North Korea, according to the complaint.

The U.S. is seeking the forfeiture of more than$ 4 million that Dandong Chengtai wired on June 21 to an affiliated company, Maison Trading Limited, use Chinese bank accounts. U.S. investigators allege Maison Trading is a front company operated by a Dandong Chengtai employee.