"Russia is an adversary and always has been," the Arkansas Republican said. "Unfortunately, it's always apt to be."
But when it comes to President Donald Trump's the federal investigation into links between his campaign and Russia, Cotton also speaks plainly.
"I think the President could be more focused and disciplined about staying on his agenda," he said. "I've communicated that publicly as well as privately to him."
Trump has made reports on Russia and his campaign the center of many Twitter rants, and both he and his press secretary Sean Spicer have blasted reporting on the subject as "fake news."
Speaking to David Axelrod on "The Axe Files," a podcast from the University of Chicago Institute of Politics and CNN, Cotton said he believes that Trump ought to shift his focus to his domestic plans.
"Donald Trump is going to do well if he's focused on things like jobs, wages and security," Cotton said. "To the extent that he's focused on all of the hair on fire, wild eyed allegations and drama around these inquiries, he's going to do less well."
Cotton, a member of the Senate intelligence committee, said he has no reason to doubt the intelligence communities' conclusions that Russia interfered or tried to interfere with the 2016 US presidential election. He also believes that Russian President Vladimir Putin was the driving force behind those efforts.
"Vladimir Putin was a KGB officer. Once a KGB officer, always a KGB officer," he said. "Russian intelligence services in particular, more so than even most intelligence services, have longstanding patterns ... of disinformation, deception, manipulation."
However, when it comes the increasing number of reported ties between the Trump campaign and Russia, Cotton said he hasn't seen indications of wrongdoing.
"As a general matter, there's nothing inappropriate about members of the transition meeting with representatives of a foreign government," Cotton said of reports that the President's son-in-law and top adviser, Jared Kushner, met secretly with both Russian ambassador Sergey Kislyak
and Russian banker Sergey Gorkov
at separate points during the transition period.
Cotton noted that he "can't evaluate what was said in conversations in private meetings or on phone calls," adding that he would like to see Kushner "turn over documents" and "tell his side of the story" to the Senate intelligence committee.
To hear the whole conversation with Cotton, click on http://podcast.cnn.com
. To get "The Axe Files" podcast every week, subscribe at http://itunes.com/theaxefiles