Russian President Vladimir Putin has built military capacity on the border of Ukraine that is "much larger and on a much more lethal scale" than preceded Russia's 2014 invasion of Crimea, Under Secretary of State Toria Nuland said Tuesday, warning of severe risks to Moscow if it invades Ukraine. 

Moscow has positioned approximately 100 tactical groups and nearly all its ready ground forces based west of the Urals at different spots along its border with Ukraine, Nuland told the Senate Foreign Relations Committee. "Much of this comes right out of Putin's 2014 playbook," Nuland said, "but this time, it is much larger and on a much more lethal scale." 

This time, the US and its allies will also respond differently to any military action against Ukraine, Nuland said. While she declined to offer specific examples in an open hearing, she said the US and European allies "will be united in imposing severe consequences on Moscow for its actions, including high impact economic measures that we have refrained from using in the past." 

'Extremely significant' 

Unlike the sanctions pursued in 2014, which escalated somewhat gradually, "this time the intent is to make clear that the initial sanctions in response to any further aggressive moves in Ukraine will be extremely significant and isolating for Russia and for Russian business and for the Russian people." 

She added that "none of us seeks confrontation or crisis. Certainly, the Russian people don't need it." 

Nuland testified hours after President Joe Biden spoke by secure video call with Putin to outline potential sanctions and other ramifications should the Russian leader move militarily against Ukraine. 

The two-hour call was just the latest diplomatic outreach meant to avoid war on European soil. 

After a meeting with Russian Foreign Minister Sergei Lavrov Thursday in Stockholm, Secretary of State Antony Blinken told reporters that the US and European allies are "deeply concerned by evidence that Russia has made plans for significant aggressive moves against Ukraine, including efforts to destabilize Ukraine from within and large-scale military operations." 

Referring to Russia's invasion of Crimea, Blinken added, "We've seen this playbook before in 2014, when Russia last invaded Ukraine." 

A recent US intelligence assessment found that the Kremlin could begin an offensive involving up to 175,000 troops staged at different points along the border with Ukraine. CNN has reported that Russia has staged enough forces, equipment and supplies, including medical units and fuel, near Ukraine's borders to sustain a drawn-out conflict. 

CIA Director Bill Burns said Monday that with those pieces in place, Putin is able to act swiftly. 

"We don't know that Putin has made up his mind to use force, but what we do know is that he's putting the Russian military, the Russian security forces in a place where they could act in a pretty sweeping way," Burns told the Wall Street Journal CEO Summit. 

- by Nicole Gaouette, Jennifer Hansler and Kylie Atwood, CNN