In a strongly worded statement foreign policy speech at the Lord Mayor's Banquet at Mansion House, May said on Monday London would do “what is necessary to protect ourselves” and allies against Moscow.
She also sent a “very simple message” to Putin, calling on the Russian head of state and his government to refrain from efforts to “weaponize information” as a means of intervention in other countries’ democracies.
"In a recent speech President Putin said that while the interests of states do not always coincide, strategic gains cannot be made at the expense of others. When a state fails to observe universal rules of conduct and pursues its interests at any cost, it will provoke resistance and disputes will become unpredictable and dangerous,” she said.
"I say to President Putin, I agree. But it is Russia’s actions which threaten the international order on which we all depend," the PM argued, adding Russia could be a valuable partner only if it "plays by the rules."
May said Russia’s interventionism began with the 2014 reintegration of Crimea to Russia in a referendum and continued by fueling the Ukraine conflict, violating European countries’ airspace and a campaign of cyber espionage and disruption.
"This has included meddling in elections and hacking the Danish Ministry of Defense and the (German governmental body) Bundestag, among many others,” she claimed.
She also accused Russia of deploying its state-run media to plant “fake stories and photo-shopped images” in order to “sow discord” in the West.
"We know what you are doing. And you will not succeed. Because you underestimate the resilience of our democracies, the enduring attraction of free and open societies, and the commitment of Western nations to the alliances that bind us,” May continued.