(CNN) US Secretary of State Rex Tillerson issued a harsh condemnation of Russia following a nerve agent attack on a former Russian spy in the United Kingdom last week, going further than the White House's response stopping short of pinning blame for the attack on Moscow.

In a Monday morning call with United Kingdom Foreign Secretary Boris Johnson, Tillerson discussed the attempted murder of former Russian double agent Sergei Skripal and his daughter Yulia in the English city of Salisbury, according to a State Department statement.

"We have full confidence in the UK's investigation and its assessment that Russia was likely responsible for the nerve agent attack that took place in Salisbury last week," Tillerson said in the statement.

He continued, "There is never a justification for this type of attack -- the attempted murder of a private citizen on the soil of a sovereign nation -- and we are outraged that Russia appears to have again engaged in such behavior. From Ukraine to Syria -- and now the UK -- Russia continues to be an irresponsible force of instability in the world, acting with open disregard for the sovereignty of other states and the life of their citizens."

The State Department's position on the attack appears be much stronger than the White House's response.

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