Kerry and Russian Foreign Minister Sergey Lavrov discussed Ukraine in a side meeting at a conference on Libya in Rome, Time magazine reported. A senior state department official said Kerry advised Lavrov to open communications with Ukraine and to allow monitors in Crimea.
"The secretary made clear the importance of the Russians talking directly to the Ukrainians, and the two discussed possible formats for how that dialogue might take place," the official said. "Secretary Kerry also pressed the importance of allowing international monitors into Crimea and eastern Ukraine to see first-hand the situation on the ground."
The meeting came as the Crimean Parliament approved a referendum on secession. Kerry in a later statement called on Russia to "de-escalate," Politico reported.
"The choices that Russia has made escalated this situation and we believe that Russia has the opportunity now, together with the rest of us, to make the right choices in order to de-escalate," Kerry said.
The State Department issued a scathing, 10-point fact sheet Wednesday targeting claims by Russian President Vladimir Putin after Russian troops seized control of the Crimean peninsula in Ukraine earlier this week, decrying the Russian government for presenting "a false narrative to justify its illegal action in Ukraine."
"The world has not seen such startling Russian fiction since [Russian novelist Fyodor] Dostoyevsky wrote, 'The formula 'two plus two equals five' is not without its attractions,'" the department said in the statement.
Tensions have risen since Russian forces entered Ukraine's autonomous, pro-Moscow Crimea region and began taking control of key infrastructure. Putin has downplayed Russia's involvement, denying the troops' existence and calling them local self-defense forces.
Pushing back, the State Department said: "Strong evidence suggests that members of Russian security services are at the heart of the highly organized anti-Ukraine forces in Crimea."
"While these units wear uniforms without insignia, they drive vehicles with Russian military license plates and freely identify themselves as Russian security forces when asked by the international media and the Ukrainian military."
The fact sheet also rejects Putin's claims that ethnic Russians and their military facilities were under threat.