The top US and Russian diplomats made no major breakthrough at talks on Ukraine on Friday but agreed to keep talking to try to resolve a crisis that has stoked fears of a military conflict.

After the talks in Geneva, US secretary of state Antony Blinken warned of a “swift, severe” response if Russia invades Ukraine after massing troops near its border and Russian foreign minister Sergei Lavrov said Moscow was still waiting for a written response to demands for security guarantees.

But both said they were open to further dialogue, and Blinken saw grounds to hope that mutual security concerns could be addressed.

“Based on the conversations we’ve had — the extensive conversations — over the past week and today here in Geneva I think there are grounds for and a means to address some of the mutual concerns that we have about security,” Blinken said.

He described the talks as “frank and substantive” and told reporters that Russia now faced a choice.

“It can choose the path of diplomacy that can lead to peace and security, or the path that will lead only to conflict, severe consequences and international condemnation,” Blinken said, adding that diplomacy would be preferable.