(KIEV, Ukraine) -- Ukraine's interior minister said that one security officer was killed and five Ukrainian troops were injured on Sunday after the country's security services began an "anti-terror" operation in Sloviansk, Ukraine. On Saturday, armed separatists seized a pair of buildings in Sloviansk. Interior Minister Arsen Avakov announced the operation Sunday morning, but did not state where it took place.
NATO Secretary General Anders Fogh Rasmussen issued a statement on Sunday expressive concern about the escalating tension. "The reappearance of men with specialised Russian weapons and identical uniforms without insignia, as previously worn by Russian troops during Russia's illegal and illegitimate seizure of Crimea," Rasmussen said "is a grave development." He then called on Russia to de-escalate the situation and pull back its troops from the area near the Ukraine border.
United Nations Secretary General Ban Ki-moon also called for cooler heads to prevail.
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