Britain’s May blames Russia for poison attack on former spy

LONDON — Britain’s prime minister said on Monday that it was “highly likely” that Moscow was to blame for the poisoning of a former Russian spy attacked with a nerve agent near his home in southern England, and she warned of possible reprisals.

The remarks by Prime Minister Theresa May, delivered in an address to Parliament, were an unusually direct condemnation of a country that Britain has, in the past, been loath to blame for attacks on its soil. Critics say the British authorities took only modest countermeasures after Russian agents poisoned a former MI6 informant in 2006 with the rare isotope polonium 210.

The prime minister, who as home secretary resisted an open inquiry into Russia’s role in that case, is under pressure to show more resolve this time. The March 4 nerve agent attack on Sergei V. Skripal, once an informant for Britain’s foreign intelligence service, and his daughter, Yulia, exposed untold numbers of bystanders to risk around public spaces in the city of Salisbury. Traces of the poison have been found at a pub and a pizza parlor visited by the Skripals.

“It is now clear that Mr. Skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by Russia,” Mrs. May said in the House of Commons. “The government has concluded that it is highly likely that Russia was responsible for the act. . ..”

She said that either the poisoning was a “direct act of the Russian state against our country” or that Moscow had lost control of its nerve agent and had allowed it to get into the hands of others.

Russia has denied any responsibility. In an interview Monday, U.S. Secretary of State Rex. W. Tillerson expressed astonishment at the use in a public space of a substance like the nerve agent. “It’s almost beyond comprehension that a state, an organized state, would do something like that,” he said. “A non-state actor, I could understand. A state actor I cannot understand why anyone would take such an action.”

Mrs. May said her government had summoned the Russian ambassador to demand an explanation, and that Britain expected a response from Russia by the end of the day Tuesday.

“We shall not tolerate such a brazen act to murder innocent civilians on our soil,” she said.

On Monday, the White House took a different approach from the secretary of state in condemning the attack, declining to point a finger at Russia.

Sarah Huckabee Sanders, the White House press secretary, said at her daily briefing: “The use of a highly lethal nerve agent against U.K. citizens on U.K. soil is an outrage. The attack was reckless, indiscriminate and irresponsible. We offer the fullest condemnation.”

But Ms. Sanders brushed off questions about whether the White House shared Britain’s view that Russia was responsible. “Right now we are standing with our U.K. ally,” she said. “I think they’re still working through even some of the details of that and we’re going to continue to work with the U.K.”

Moscow has insisted that it played no role in the attack, and did so again on Monday.

“This is a circus show in the British Parliament,” the Russian Foreign Ministry spokeswoman, Maria Zakharova, told journalists in Moscow, according to the Interfax news agency.