Carter made the remarks during a NATO defense ministers meeting in Brussels on Thursday, a day after Russia fired 26 long-range cruise missiles from its warships in the Caspian Sea against Daesh (ISIL) positions in Syria.
On September 30, Russia launched an air campaign against foreign-sponsored terrorists wreaking havoc in Syria.
Carter said the Russian military campaign against ISIL "will have consequences for Russia itself, which is rightly fearful of attacks.”
"In the coming days, the Russians will begin to suffer from casualties," the Pentagon chief claimed.
Carter accused Moscow of being reckless in its military commitment, risking clashes with US aircraft in Syria.
"They have shot cruise missiles from a ship in the Caspian Sea without warning; they have come within just a few miles (kilometers) of one of our unmanned aerial vehicles," he said.
Russian Defense Ministry spokesman Major General Igor Konashenkov called Ashton’s perdition "cynical".
Earlier, three unnamed US military officials claimed that some cruise missiles fired from Russian ships at targets in Syria landed in Iran on Wednesday.
In response, the Russian Defense Ministry statement said that the new Kalibr-NK cruise missiles all struck within nine feet of their intended targets in Syria.
The missiles landed in Raqqa, Idlib and Aleppo provinces and they destroyed ISIL positions, including training camps and ammunition depots.
"No matter how unpleasant and unexpected it is for our colleagues in the Pentagon and Langley, our strike yesterday with precision-guided weapons at ISIS (Daesh/ISIL) infrastructure in Syria hit its targets," the Russian Defense Ministry spokesman said.