While speaking on the Senate floor on Wednesday, Sen. John McCain (R-AZ) accused Sen. Rand Paul (R-KY) of working for Russian President Vladimir Putin.
McCain made the remark after Paul blocked an attempt to vote on a bill advancing Montenegro's bid to join the North Atlantic Treaty Organization (NATO).
The Arizona Senator said that if Paul opposed the treaty, "You are achieving the objectives of Vladimir Putin... trying to dismember this small country which has already been the subject of an attempted coup."
Paul's office released an official statement on Wednesday evening in response to the comments and explaining his objection to Montenegro's bid.
"Currently, the United States has troops in dozens of countries and is actively fighting in Iraq, Syria, Libya, and Yemen (with the occasional drone strike in Pakistan)," the statement read.
"In addition, the United States is pledged to defend 28 countries in NATO. It is unwise to expand the monetary and military obligations of the United States given the burden of our $20 trillion debt."
You can watch McCain's remarks below.