Russian President Vladimir Putin put his country’s nuclear deterrence forces on high alert Sunday amid a growing global backlash against Russia’s invasion of Ukraine. Despite the escalation, Ukraine’s Defense Ministry said representatives for Ukraine and Russia have agreed to meet on the Ukraine-Belarus border “with no preconditions.”Meanwhile, the Russian advance into Ukraine continues. Russian military vehicles entered Ukraine’s second-largest city Kharkiv with reports of fighting taking place and residents being warned to stay in shelters.The capital of Kyiv remained under Ukrainian control, with a key official in Kyiv’s city administration asserting that “the capital is completely controlled by the Ukrainian army and defense.”Here are links to additional CNBC coverage of the Russian invasion of Ukraine:Public support for Russian President Vladimir Putin will wane if people “wake up tomorrow or today and they see suddenly that their savings are worth a quarter of what they were on Friday. That has an impact,” said Douglas Rediker, a nonresident senior fellow at Brookings Institute. Western nations could roll out further sanctions targeting the Russian leader’s inner circle, such as the oligarchs, which could undermine his grip on power, said Rediker.If the oligarchs are “never going to see their yachts” again or “never going to be able to go to that mansion”  — that potentially has “a chilling effect on their lives, their wealth accumulation, and their support for Putin,” he noted. “I think you’re certainly going to see more granularity than what was announced over the past seven years,” he told CNBC’s “Squawk Box Asia” on Monday. “You are going to see the list of banks that are included in the SWIFT sanctions protocol. You’re going to see oligarchs that are named. I would look for some high-profile seizures of mansions and yachts and jets in the coming days,” he added.The U.S., European allies and Canada agreed Saturday to remove key Russian banks from the interbank messaging system, SWIFT, which serves as an internal messaging system between more than 11,000 banks and financial institutions in over 200 countries and territories. The move is an extraordinary step that will sever the country from much of the global financial system.cnbc.com