LONDON (AP) — A former head of Britain's overseas intelligence agency says Brexit could leave Britain more vulnerable to attacks like the nerve-agent poisoning of a former Russian spy in Salisbury.

John Sawers, who led MI6 between 2009 and 2014, says "I don't believe Russia would have used a nerve agent on the streets of an American or German city" because the consequences would be too great.

He says Britain's "very weakness — as a result of Brexit, as a result of fraying trans-Atlantic ties — was an attraction for Russia."

Sawers gave a speech Friday in Salisbury, where spy Sergei Skripal and his daughter Yulia were poisoned in March with the nerve agent Novichok.

Britain says the attack was ordered at a senior level of the Russian government, a claim Moscow denies.