Sen. John McCain (R-Ariz.) on Tuesday said the resignation of President Trump’s national security adviser, Michael Flynn, shed light on the “dysfunction” of the country’s national security operation.

In a statement, McCain thanked Flynn for his “many years of distinguished service to our country” and wished him “the very best in his future endeavors.”

“At the same time, General Flynn’s resignation is a troubling indication of the dysfunction of the current national security apparatus,” McCain said.

{mosads}”As our nation confronts the most complex and diverse array of global challenges since the end of the World War II, it is imperative that the president select a new National Security Adviser who is empowered by clear lines of authority and responsibility and possesses the skills and experience necessary to organize the national security system across our government.”

The Arizona Republican also said Flynn’s resignation raises further questions about the Trump administration’s “intentions” toward Russian President Vladimir Putin.

“Including statements by the President suggesting moral equivalence between the United States and Russia despite its invasion of Ukraine, annexation of Crimea, threats to our NATO allies, and attempted interference in American elections,” McCain said.

McCain appeared to be referring to the president’s comments earlier this month when he pushed back on Bill O’Reilly’s description of Putin as a “killer.” In response to a question about Putin, the president said: “There are a lot of killers. We’ve got a lot of killers. What, you think our country is so innocent?”

McCain on Tuesday also called for American policy toward Russia to be made “clear and unequivocal.”

“We will honor our commitments to our NATO allies, we will maintain and enhance our deterrent posture in Europe, we will hold Russian violators of human rights accountable for their actions, and we will maintain sanctions on Russia so long as it continues to violate the sovereignty and territorial integrity of Ukraine,” McCain said.

McCain said he looked forward to working with the Trump administration in his role as chairman of the Senate Armed Services Committee to “defend the nation and support our military service members.”

Flynn resigned late Monday after reports he misled senior Trump White House officials about his conversations with Russia’s ambassador to the U.S.

His future in the White House had come under speculation since reports surfaced last week that he talked about sanctions before Trump was sworn in.

Flynn blamed his resignation late Monday on the “fast pace of events” that led him to “inadvertently” give Vice President Mike Pence and others “incomplete information” about his phone conversations with the ambassador.

He said the president and vice president have accepted his apology.