WASHINGTON (Reuters) - The United States held out the possibility on Monday that the U.S. and Russian foreign ministers could meet this week about Ukraine but said it needed to know Moscow would engage seriously on a diplomatic solution.
Russia's bloodless seizure of the Crimea region of Ukraine has brought U.S.-Russian relations to one of their lowest points since the Cold War, with the United States searching for a way to keep Russia from annexing Crimea and its Russian naval base.
The State Department said Secretary of State John Kerry told Russian Foreign Minister Sergei Lavrov on Saturday Washington wanted Moscow to cease its military advances in Ukraine, stop its drive to annex Crimea and end "provocative steps."
"The United States needs to see concrete evidence that Russia is prepared to engage on the diplomatic proposals we have made to facilitate direct dialogue between Ukraine and Russia and to use international mechanisms like a contact group to deescalate the conflict," State Department spokeswoman Jen Psaki said in a written statement.
"Kerry made clear to Foreign Minister Lavrov that he would welcome further discussions focused on how to de-escalate the crisis in Ukraine if and when we see concrete evidence that Russia is prepared to engage on these proposals," she added.
Separately, Psaki told reporters it was conceivable Kerry might meet Lavrov prior to a planned referendum within Crimea on whether to join Russia but he first wanted to ensure that Moscow would engage seriously on U.S. diplomatic proposals.
Unidentified armed men fired in the air as they moved into a Ukrainian naval post in Crimea on Monday in the latest confrontation since Russian military groups seized control of the Black Sea peninsula.
With diplomacy at a standstill, Russia said the United States had spurned an invitation to hold new talks on resolving the crisis, the worst East-West standoff since the Cold War.
Lavrov said he had invited Kerry for talks in Russia on Monday on Russian President Vladimir Putin's instructions, but said Kerry on Saturday said he wanted to postpone such talks.
A U.S. official who spoke on condition of anonymity said the United States wanted Russia to agree to some kind of a format such as an international "contact group" that would enable Russia, Ukraine and other nations to discuss the issue.
'NO, NO, NO, NO, NO'
"The point is we're not going to just walk into something where they are just going to say 'no, no, no, no, no,' to everything and we have travelled all the way there," the official said. "We're not going to just go there and be rolled."
Last week, Putin's spokesman ridiculed proposals for an international contact group, saying they "make us smile."
Many Western nations have denounced the referendum as illegitimate, saying Ukraine's constitution calls for such votes to be held nationwide rather than within individual regions.
White House spokesman Jay Carney kept up the criticism.
"We are long past the days when borders can be redrawn over the heads of elected governments," he said.
He also hinted the United States, which on Thursday ordered sanctions including travel bans and the freezing of U.S. assets on people responsible for Russia's intervention in Crimea, might impose more sanctions depending on the outcome of the referendum.
Separately, U.S. President Barack Obama began a new week of diplomatic consultations on Ukraine with a phone call on Sunday to Chinese President Xi Jinping that focused on a peaceful solution to Russia's military intervention.
A White House statement released on Monday gave little detail as to what was discussed, saying the two agreed on the "importance of upholding principles of sovereignty and territorial integrity, both in the context of Ukraine and also for the broader functioning of the international system."
Obama also phoned Spain's Prime Minister Mariano Rajoy and Kazakh President Nursultan Nazarbayev, the White House said.
(Additional Reporting by Alexei Anishchuk and Roberta Rampton; Editing by Susan Heavey and Tom Perry)