The US is prepared for diplomacy as well as adopting economic measures against Russia in the event of any aggression against Ukraine, National Security Adviser Jake Sullivan said Thursday. 

"We're prepared to continue with diplomacy to advance security and stability in the Euro Atlantic. We're equally prepared if Russia chooses a different path," Sullivan told reporters at the White House.

"We continue to coordinate intensively with partners on severe economic measures in response to a further Russian invasion of Ukraine," he added.

Washington has just concluded an intensive week of diplomacy with multiple formats, including the Strategic Stability Dialogue, the NATO-Russia Council talks and a meeting of the Organization for Security and Co-operation in Europe (OSCE).

During the talks, Sullivan said Russia raised its concerns and the US raised its concerns, including "the actions Russia has taken to undermine European security."

"The discussions were frank and direct. They were useful. They gave us and our allies things to consider. They gave Russia things to consider," he said.

"We will now reflect and consult with allies and partners on how to proceed."

The US and its European allies have warned of massive consequences should Russia renew hostilities against Ukraine and invade the Eastern European country. Moscow has continued to amass its forces on its border with Ukraine but has denied that it is preparing for an invasion.

On Wednesday, Deputy Secretary of State Wendy Sherman said if Russia further invades Ukraine, there will be significant costs and consequences well beyond what they faced in 2014.

She urged Russia to keep talking.

"If Russia walks away, however, it will be quite apparent that they were never serious about pursuing diplomacy at all. That is why collectively we are preparing for every eventuality," said Sherman at a news conference at NATO headquarters in Brussels.