The Trump administration on Thursday retaliated against Russia for expelling hundreds of U.S. diplomats, announcing Moscow will be required to close several posts in major American cities.

The State Department, in a statement that warned of a “downward spiral” in relations, said Russia must close its consulate general in San Francisco as well as its chancery annex in Washington, D.C., and consular annex in New York City.

“These closures will need to be accomplished by September 2,” spokeswoman Heather Nauert said in the statement.

The decision was in retaliation for Russian President Vladimir Putin kicking out more than 700 U.S. diplomats – after Trump, reluctantly, signed a sanctions law passed by Congress.

While calling the Russian order “unwarranted,” Nauert said Thursday that the U.S. has “fully implemented” the reduction of the U.S. mission in Russia. She described the new demand on Moscow to reduce its presence in the United States as being “in the spirit of parity invoked by the Russians.”

“With this action both countries will remain with three consulates each,” she said. “While there will continue to be a disparity in the number of diplomatic and consular annexes, we have chosen to allow the Russian Government to maintain some of its annexes in an effort to arrest the downward spiral in our relationship.”

She said the U.S. hopes “we can avoid further retaliatory actions by both sides and move forward to achieve the stated goal of both of our presidents: improved relations between our two countries and increased cooperation on areas of mutual concern.”

She added, “The United States is prepared to take further action as necessary and as warranted.”

Earlier this month, Trump signed a bill imposing sanctions on Russia after the legislation overwhelmingly passed the House and Senate. The sanctions stemmed from Russia’s invasion of Crimea in 2014 and its attempted interference in the United States’ presidential election in 2016.

After Congress passed the sanctions in July, Putin said 755 U.S. diplomats would be expelled from Russia by Sept. 1.