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."

Trump, who has repeatedly reached out to Putin to build relations, mused last month about inviting him to an expanded summit of the Group of Seven industrial democracies -- which kicked out Russia over its takeover of Crimea.

Secretary of State Mike Pompeo, seen here in February 2020, says the Trump administration has raised concerns with Russia over Afghanistan
Secretary of State Mike Pompeo, seen here in February 2020, says the Trump administration has raised concerns with Russia over Afghanistan AFP / MANDEL NGAN

Weeks later, Washington has been in uproar over reports, initially in The New York Times, that Russian intelligence offered bounties to Taliban-linked militants to target troops of the US-led coalition in Afghanistan.

Pompeo, while saying he would not discuss the intelligence, said the United States has long voiced concern to Russia.

"The Russians have been selling small arms and put Americans there at risk for 10 years, and we have objected to it," he said.

"When we see credible information that suggests that the Russians are putting American lives at risk, we're responding in a way that is serious," he said.

"Do we warn them, do we talk to them? I think the answer is, of course we do."