Former Defense Secretary Robert Gates questioned Donald Trump’s foreign policy positions on Sunday, saying the presumptive Republican presidential nominee seems unwilling to accept advice from others and thinks he “has all the answers.”

{mosads}“He seems to think that he has all the answers and that he doesn’t need any advice from staff or anybody else,” Gates said on “Face the Nation” on CBS. “And that he knows more about these things than anybody else and doesn’t really feel the need to surround himself with informed advisers.”

Gates, who served as Defense secretary from 2006 to 2011 under former President George W. Bush and President Barack Obama, specifically questioned Trump’s relationship with Russian leader Vladimir Putin and comments the real estate mogul has made about China.

“I think there are some contradictions. You can’t have a trade war with China and then turn around and ask them to help you on North Korea. … I have no idea what his policy would be in terms of dealing with [the Islamic State in Iraq and Syria]. I worry a little bit about his admiration for Vladimir Putin.”

Gates also said it’s unlikely he would serve Trump if asked.

“I learned a long time ago never to say never, but let’s just say that would be inconceivable to me. Before the election, I will be 73, and let’s just say I’ve stopped working on my resume.”