Mike Pompeo doesn't rule out inviting Russia's President Vladimir Putin to expanded G7 summit

US Secretary of State Mike Pompeo.

Secretary of State Mike Pompeo on Wednesday left the door open to President Vladimir Putin attending a US summit but insisted the administration has been firm over Moscow's activities in Afghanistan.

President Donald Trump "gets to decide if he wants him to come to a summit or not. That's his decision," Pompeo told reporters.

"I'll certainly leave that to him. But I do believe it is absolutely important that we have more frequent engagement with the Russians."