Global leaders remain in an impasse over the situation in Ukraine, with Secretary of State John Kerry refusing to negotiate with his Russian counterpart and Russia refusing to accept deposed Ukrainian President Viktor Yanukovych's ouster, as Crimea nears a referendum vote on whether or not to secede.

Yanukovych speaks. REUTERS/Maxim Shemetov 

On Monday, Russia announced that Kerry's diplomatic proposals for negotiation with Ukraine, presented to Russian Foreign Minister Sergei Lavrov over the past week, were unacceptable because they take "the situation created by the coup as a starting point." Russia is standing by deposed Yanukovych, who has been sheltering in Russia since he fled his Kiev compound last month. In a televised address, Yanukovych said that a "gang of ultra-nationalists and fascists are running the country," adding:

Soldiers and officers understand what you're worth and they will not fulfill your order. I remain not only the legal president, but the chief commander. I did not turn down my authority, and I am alive. They say in the U.S. that I ran from the country. I repeat: I did not run. as armed people basically attempted a coup with arms, I was still on the territory of Ukraine. As soon as circumstances allow. I am convinced it's not long to wait. I will return to Kyiv.

Russian officials did not respond to a set of questions Kerry posed over the weekend -- notably, whether Russian leaders would meet and negotiate with members of the Ukrainian interim government. Now, it is unlikely Kerry will meet with officials before the March 16 referendum, said State Department spokeswoman Jen Psaki in a statement

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... 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.

A man waves a Crimean flag.  REUTERS/Vasily Fedosenko 

While Kerry takes a steely step back, Western leaders continue to actively pressure Moscow to stand down. French Foreign Minister Laruent Fabius said that Russia could see sanctions, like the freezing of assets and travel blocks, as soon as this week if it doesn't cooperate with Kerry's proposal. And Ukraine's interim Prime Minister Arseniy Yatsenyuk will meet with President Obama in the White House on Wednesday to discuss U.S. plans to contribute economic aid to the struggling country. 

Even as diplomatic tensions heat up, Russia continues to deny any military presence in Ukraine, saying that all troops on the ground are Crimean "self-defense" forces. This seems to fly in the face of reports from Crimea, where the situation remains volatile and every day brings a new crisis. Today, entry and exit into the region has been reportedly blocked -- except for flights coming from Moscow:  

Officials in Kiev are determined to hold on to Crimea. Earlier, they announced that they will form a new national guard to protect Crimea and today the interim government issued Crimea an ultimatum, saying it will dissolve the region's semi-autonomous government if the referendum vote is not called off.