On Friday, the US State Department announced plans to give Ukraine military assistance to help protect its territorial integrity.
"The United States crossed the line in a sense by announcing a decision to supply weapons of destructive power [to Ukraine]… The US weapons may lead to new victims in a country that is neighboring us, therefore we cannot remain indifferent," Ryabkov said in a statement.
Ukraine, which has been engaged in a military conflict in the southeastern region of Donbass for three years, has repeatedly asked the United States for lethal and non-lethal weapons.
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Russia has objected to this, warning that arms deliveries to Ukraine would only escalate the conflict.