Speaking at a conference in Kiev, Ukraine on Tuesday, Lloyd Austin was defiant that the US would stand by its Ukrainian allies in the face of growing Russian aggression as the war in the Donbass region enters its eighth year.
Mr Austin went on to demand that Russia bring an end to its cyberattack campaigns which earlier this year infiltrated a host of major US government networks.
He added how these “persistent cyber attacks” and other “malign activities” against the United States, its allies, and partners will not be tolerated.
The Defence Secretary went on to slam Russia for starting the war before branding how Russia’s President Putin is an “obstacle to a peaceful resolution” to the conflict.
While in a defiant conclusion, he said how “Ukraine “has a right to decide its own future foreign policy” adding “we expect that they will be able to do that without any outside interference”.
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Fighting erupted soon after Russia seized the Crimea peninsula from Ukraine in an almost bloodless seizure of power which saw troops flood streets without Russian insignia.
Russia also denies carrying out cyberattacks against its enemies despite evidence to the contrary from US intelligence services.
The most recent uptick in tensions follows news on Monday that Moscow is ending the activities of its diplomatic mission to NATO after the Western military alliance expelled eight Russians it accused of spying.
Following the decision, Foreign Minister Sergei Lavrov slammed: “If NATO members have any urgent matters, they can contact our ambassador in Belgium on these questions.”