Russia ‘very likely’ to invade Ukraine without ‘enormous sanctions’ – Schiff

Russia is “very likely” to invade Ukraine and might only be deterred by “enormous sanctions”, the chair of the US House intelligence committee said on Sunday.

Related: Ukraine crisis: how Putin feeds off anger over Nato’s eastward expansion

Adam Schiff also said an invasion could backfire on Moscow, by drawing more countries into the Nato military alliance.

“I also think that a powerful deterrent is the understanding that if they do invade, it is going to bring Nato closer to Russia, not push it farther away,” he said.

After the California Democrat spoke, the White House said Joe Biden had spoken to the Ukrainian president, Volodymyr Zelenskiy.

Jen Psaki, the White House press secretary, said in a statement: “President Biden made clear that the United States and its allies and partners will respond decisively if Russia further invades Ukraine.”

On Twitter, Zelenskiy said: “The first international talk of the year with [Biden] proves the special nature of our relations.”

He also said the joint actions of Ukraine, the US “and partners in keeping peace in Europe, preventing further escalation, reforms, deoligarchisation were discussed. We appreciate the unwavering support of Ukraine.”

Russia has amassed around 100,000 troops near its border with Ukraine. Earlier this week, Biden told Vladimir Putin the US would impose serious sanctions if Russia attacked.

Talks are scheduled for Geneva on 9 and 10 January. But amid tensions heightened by both sides’ possession of nuclear weapons, Russia’s foreign minister, Sergei Lavrov, said that if “the west continues its aggressive line, Russia will be forced to take all necessary measures to ensure strategic balance and eliminate unacceptable threats to our security”.

Russia has for years complained about Nato encroachment. Ukraine is not a member of the alliance, which guarantees collective defence, but Nato has expanded eastwards since the fall of the Soviet Union and Kiev urgently seeks admission.

Russia invaded Ukrainian territory in 2014, annexing Crimea.

The US has supplied “small” arms to Ukraine.

On CBS’s Face the Nation, Schiff was asked what would stop Putin ordering an invasion.

“I think that it would require enormous sanctions on Russia to deter what appears to be a very likely Russian invasion of Ukraine again,” Schiff said. “And I think our allies need to be solidly on board with it. Russia needs to understand we are united in this.”

Related: Ukraine urges Nato to hasten membership as Russian troops gather

An invasion, Schiff said, would see “more Nato assets closer to Russia. [It] will have the opposite impact of what Putin is trying to achieve”.

Schiff said he had “no problem” with “going after Putin personally”, but thought “sector-sized sanctions will be the most important”.

Asked if he thought scheduled talks had any chance of averting an invasion, he said: “I fear that Putin is very likely to invade. I still frankly don’t understand the full motivation for why now he’s doing this, but he certainly appears intent on it unless we can persuade him otherwise.

“And I think nothing other than a level of sanctions that Russia has never seen will deter him, and that’s exactly what we need to do with our allies.”

• Reuters contributed to this report