A bipartisan group of lawmakers is calling on the administration to further crack down on the growing ties between China and Iran, urging the administration to “fully enforce” U.S. sanctions on Iran, which have been repeatedly violated by Chinese entities.

Reps. Josh Gottheimer (D-NJ) and Claudia Tenney (R-NY), joined by 19 colleagues, wrote to Secretary of State Tony Blinken on Tuesday outlining a number of areas of growing cooperation between the two U.S. rivals, which the lawmakers say “cannot be tolerated.”

“The Chinese-Iranian alliance presents a unique challenge and dangerous partnership antithetical to American national security interests,” their letter, obtained by Jewish Insider, reads.

The letter highlights China’s “rapidly increasing” imports of Iranian oil, in “willful disregard” of the U.S.’ sanctions on Iran’s oil trade. The letter argues that this trade “reduces economic pressure on Iran to end its pursuit of nuclear weapons, support for terrorism, and continued bankrolling of malign activities around the world.”

Amid escalating criticisms from conservatives that the Biden administration is — potentially wilfully — under-enforcing U.S. sanctions on Iran, the lawmakers called for the State Department to “fully enforce all U.S. sanctions on Iran by designating Chinese entities that violate them.”

The lawmakers also raised concerns about the reports that China is considering supplying a ballistic missile propellant chemical to Iran.

“It is dangerous and unacceptable for China to assist Iran’s missile program, and we encourage the Administration to do everything in its power to stop the sale of AP,” the letter continues.

The letter further notes China’s continued provision of drone components to Iran, some of which ultimately find their way to Russia for use in its invasion of Ukraine and others of which are used in attacks on oil tankers in the Gulf.

“In the Middle East, our focus remains on eliminating radical, ideologically motivated terror and promoting stability and peace. The success of both of these efforts depends on maintaining our strong bilateral relationship with Israel,” the letter continues. “Above all, we must prevent Iran from ever acquiring nuclear weapons and threatening our greatest ally in the region. Yet, China’s activities in the Middle East make these already complicated challenges more difficult and dangerous.”

The letter was co-signed by Reps. Brian Fitzpatrick (R-PA), Jeff Van Drew (R-NJ), Donald Norcross (D-NJ), Abigail Spanberger (D-VA), Maria Elvira Salazar (R-FL), Mike Lawler (R-NY), Nancy Mace (R-SC), Lori Chavez-DeRemer (R-OR), Rich McCormick (R-GA), Nicole Malliotakis (R-NY), Max Miller (R-OH), Cory Mills (R-FL), Darren Soto (D-FL), Darrell Issa (R-CA), Doug Lamborn (R-CO), Jared Moskowitz (D-FL), Tom Kean (R-NJ), Don Davis (D-NC) and Wiley Nickel (D-NC).