President Donald Trump is ordering the expulsion of 60 Russian intelligence officers and the shuttering of their consulate in Seattle in response to a recent chemical assassination attempt on U.K. soil, senior administration officials told reporters Monday.

The actions are in response to the alleged use of a nerve agent by the Russian government against a Russian dissident living in the United Kingdom, Sergei Skripal. Skripal was critically wounded in the attack along with his daughter, and a U.K. police officer is also suffering symptoms.

Senior administration officials explained that the Russian consulate in Seattle was being closed due to its proximity to a U.S. naval base. Officials said 12 of the 60 officers being expelled were masquerading as diplomats at the Russian mission at the United Nations.

“When you attack our friends you will face serious consequences,” a senior administration official declared noting that “dozens” of officials were being expelled. Another official stated that this expulsion will significantly “curtail” its governments attempts to spy on U.S. citizen by reducing the number of known intelligence officers in the U.S. by half.

British Prime Minister Theresa May similarly expelled Russian diplomats from her country in response to the attack.