The United States warned Russia on Sunday about assisting any potential Iranian attempts to evade an upcoming round of U.S. sanctions against the Islamic Republic, scheduled to take effect on Nov. 4, months after U.S. President Donald Trump withdrew America from the 2015 nuclear deal.

“Iran might be pushing the idea of Russia selling their oil on the world market to evade sanctions,” a senior administration official told The Financial Times. “I would discourage Russia from even considering this. It would be in Russia’s best interests not to facilitate Iranian evasion of U.S. sanctions.”

This development comes as U.S. National Security Advisor John Bolton is expected to meet senior Russian officials in Moscow early next week.

Russia supported the nuclear deal and supports Iran’s proxies, such as Syrian President Bashar Assad and Hezbollah in Lebanon.

Additionally, U.S. Treasury Secretary Steve Mnuchin, visiting Israel this week, said on Sunday that it will be difficult for countries to receive waivers on Iran oil sanctions.

“I would expect that if we do give waivers, it will be significantly larger reductions,” he said in an interview with Reuters.

In light of Bolton’s remarks in August about completely eliminating Iranian oil exports, “I don’t expect we will get to zero in November, but I do expect we will eventually get to zero,” added Mnuchin. “There have been already very significant reductions in advance of this date.”