China bears significant blame for Iran’s success in developing a dangerous new array of ballistic missiles, a top White House adviser said the same day the administration imposed significant new sanctions on the Middle Eastern regime.

Tim Morrison, the National Security Council’s senior director for weapons of mass destruction, asked allies to join the United States in rebuking Beijing for protecting an arms dealer who has made Iran's weapons programs possible.

“We call on all governments that maintain ties with Beijing to make this a priority,” Morrison said Wednesday. “For U.S. allies, especially those in the Gulf that face the threat of Iranian missiles every day, this should be a priority in the relations with China.”

Morrison’s complaint centered on Chinese officials allowing “a key broker for Iran's ballistic missile program” to operate with impunity for more than a decade. Businessman Li Fangwei, also known as Karl Lee, has helped the regime modernize an arsenal of ballistic missiles that play a central role in its military plans. The dealer’s operations have aided Iran’s nuclear weapons program and strengthened the regime’s ability to threaten American forces with conventional weapons.

"Pick any Iranian missile at random and open it up, and there's a good chance you'll find a part inside that was supplied by Li Fang Wei," a Vice magazine profile stated. The FBI offers a $5 million reward for information leading to Li's arrest. China refuses to hand over Li, 46, for extradition, saying it "resolutely opposes the US citing domestic laws to unilaterally impose sanctions on Chinese companies or individuals."

“The equipment and components that Lee has provided to Iran have contributed to Iran's development of more advanced missiles with improved accuracy, range, and lethality,” Morrison said at the launch of the Foundation for Defense of Democracies' Center on Military and Political Power. “Iran now fields an array of short- and medium-range ballistic missile systems capable of threatening deployed U.S. forces, allies, and partners, and Lee remains a fugitive from justice.”

Morrison's speech came on the first anniversary of President Trump’s withdrawal from the 2015 Iran nuclear deal. Iranian officials took the occasion to announce the regime would stop complying with some aspects of the agreement, including limits on stockpiling enriched uranium, and threaten to go further if Europe doesn't help insulate the country from American sanctions. Trump responded by sanctioning Iran's metal industries, 10% of its export economy.

China, which supports the nuclear deal, marked the anniversary by accusing the United States of “heighten[ing] tensions surrounding the Iranian nuclear issue." “We call on relevant sides to exercise restraint and step up dialogue to prevent a spiral of escalation of tensions,” Chinese foreign ministry spokesman Geng Shuang said Wednesday.

Geng’s exhortation came hours after Secretary of State Mike Pompeo made a surprise visit to Iraq Tuesday, canceling his Berlin trip because of concern Iran is planning “imminent” attacks against Americans. U.S. officials have highlighted "intelligence showing that Iran is likely moving short-range ballistic missiles aboard boats in the Persian Gulf” to explain why Trump’s top advisers are worried about an Iranian attack in the region.

Morrison’s comments redirected the blame for those tensions back to China’s decision to allow Lee to help Iran flout international sanctions.

“Yet despite a warrant out for his arrest, more than a decade of imposing sanctions on Lee under U.S. law, and multiple media stories documenting his support for Iran, the Chinese government to date has failed to take effective action to end his proliferation activity and bring him to justice,” Morrison said. “Does China's government truly lack the means to deal with such criminal conduct in its own country? Does anyone in this room believe that?”