Donald Trump has not ruled out sending peacekeeping troops to Ukraine, the US president's peace envoy said on Monday.
"The policy has always been to take no options off the table," General Keith Kellogg told reporters after meeting with European NATO allies in Brussels.
"You don't want to get into a negotiating position where options are being considered," he added.
General Kellogg's words will serve as reassurance to European leaders fearful that they will have to shoulder the entire burden of controlling any ceasefire brokered by Trump and Putin.
The leaders of Britain, France and Germany clashed over sending troops to Ukraine at emergency talks in Paris to formulate a response to the US President's decision to open peace talks with Vladimir Putin.
General Kellogg separately briefed the North Atlantic Council, NATO's political decision-making body, as part of a broader effort to involve European countries in the process.
In an attempt to counter fears that Ukraine would be forced to accept an unsatisfactory deal, Trump's envoy said: "He [Volodymyr Zelensky] will and the people of Ukraine will accept that call."