US Secretary of State John Kerry said Wednesday that "intense discussions" with Russia and Ukraine would continue in the coming days in the hope of securing a de-escalation of current tensions between them.
"We initiated a process today that we hope will eventually lead to de-escalation," Kerry told reporters after a day of diplomatic negotiations in Paris ended with Russia refusing to bow to Western demands for direct talks with the new Ukraine government.
Kerry said he would continue talks with Russian Foreign Minister Sergei Lavrov in Rome on Thursday, where both will be for a meeting on Libya.
He said Wednesday's discussions had been constructive.
"I'd rather be where we are today than yesterday."
Kerry added: "I will be in touch with the foreign minister and prime minister of Ukraine later tonight."
"We had very thorough discussions today.
"This is hard, tough stuff. This is very serious."
Kerry played down Lavrov's refusal to meet his Ukrainian counterpart in Paris, saying he had harboured "zero expectation" of that happening.
He also insisted that sanctions against Russia were still an option but stressed: "We would prefer to find an appropriate diplomatic solution to this."
"We made it clear that the decision to go to Crimea is not without cost.
"Now we need to go forward and see if we avoid everybody being put in a corner where it's more and more difficult to find the path that presents you with the solution of dialogue.
"I was encouraged today that Russia indicated that they would prefer to see us be able to find that path.
"That's the beginning of a negotiation."