US vice president Mike Pence has said the United States will "hold Russia accountable" even as Donald Trump searches for common ground with Vladimir Putin's administration.
Mr Pence told the Munich Security Conference in Germany that the international community must also demand that Russia honours a 2015 peace agreement aimed at ending the fighting in eastern Ukraine between government forces and Moscow-backed separatists.
He also offered assurances over the US commitment to Nato and the European Union in his address to the international conference of foreign diplomats and defence officials.
Mr Pence's speech comes amid concerns in Europe about Russian aggression and US president Mr Trump's positive statements about his Russian counterpart, Mr Putin.
Mr Pence declared: "Know this: The United States will continue to hold Russia accountable, even as we search for new common ground which, as you know, President Trump believes can be found."
Mr Pence also reinforced the Trump administration's message that Nato members must spend more on defence.
The 28 member countries committed in 2014 to spending 2% of their gross domestic product on defence within a decade. But only the US and four other members of the post-Second World War military coalition are meeting the standard, Mr Pence said.
Failure to meet the commitment, he said, "erodes the very foundation of our alliance".
The US vice president added: "Let me be clear on this point: The president of the United States expects our allies to keep their word, to fulfil this commitment and, for most, that means the time has come to do more."
Mr Pence will meet German chancellor Angela Merkel later.
She addressed the conference just before the US vice president, stressing the need to maintain international alliances and saying that Nato is "in the American interest".
Mrs Merkel appealed to the United States and others to support and bolster multilateral organisations such as the European Union and United Nations, as well as Nato.
Mrs Merkel told the gathering of other world leaders, diplomats and defence officials that "acting together strengthens everyone".
Her address came amid concern about the Trump administration's approach to international affairs and fears that it may have little interest in working in multilateral forums.
Mrs Merkel asked: "Will we be able to continue working well together, or will we all fall back into our individual roles?
"I call on us - and I hope we will find a common position on this - let's make the world better together and then things will get better for every single one of us."