US Secretary of State Anthony Blinken said on Friday evening that he believed there were still opportunities to resolve the crisis diplomatically with Russia.
Asked if he was close to war, he told ABC News that the question should be asked of Russian President Vladimir Putin.
Blinken went on to say that the United States would provide in writing some of its and its allies' deepest concerns about Russia's actions.
The US Secretary of State claimed that Russia continues to aggravate the situation near the Ukrainian border, rather than reduce it.
He warned:
We made it clear to the Russians that any entry of Russian troops into Ukrainian territory would be met with a swift, unified and strong response.