Republican Sen. John Thune said Tuesday that the resignation of Mike Flynn as President Trump’s national security adviser is a positive step toward getting the focus back on the country’s national security issues.

The South Dakota senator said on CNN that Flynn acted inappropriately by speaking to the Russian ambassador to the U.S. before Trump took office, and then lying to Vice President Mike Pence about the topic of conversation. Flynn reportedly indicated to Ambassador Sergey Kislyak sanctions handed down by President Obama could be eased following Trump’s inauguration.