CNN  — 

Vitali Klitschko, the former heavyweight boxer and now the mayor of Kiev, has sent a strong warning to Russia about the presence of its troops near the Ukraine border saying “we prepare for any case.”

“If escalation goes up … We have to be ready to defend our independence and integrity of our country – and civil defense also have [sic] to be prepared,” Klitschko told CNN’s Lynda Kinkade on “Connect the World” Wednesday.

“We hope this never happens, this [is] worst case, but we have to be prepared,” the former world heavyweight champion added.

There has been months of tension near the Ukraine-Russia border, where more than 100,000 Russian soldiers have massed.

Klitschko said he is “worried” about Russian military forces at the border but says it is a possibility that what is being witnessed is merely a matter of optics, calling Russian tactics a “muscle game.”

Russia has not committed to de-escalate after two rounds of diplomatic talks this week, Deputy US Secretary of State Wendy Sherman said Wednesday.

Moscow is demanding security guarantees from the US and NATO, including a binding pledge that NATO won’t expand farther east and will not allow Ukraine to join the military alliance – something NATO is unwilling to do.

During Wednesday’s roughly four-hour meeting – which went on longer than scheduled – Sherman said that the US and its NATO allies made clear that Russia’s demand Ukraine never be permitted to join NATO was a non-starter.

The talks with the NATO-Russia Council is the second of three sets of meetings this week. They are sandwiched between Monday’s US-Russia talks and Thursday’s meeting between Russa and the Organization for Security and Cooperation in Europe.