The Biden administration along with Democratic and Republican lawmakers on Tuesday issued forceful warnings to Russian President Vladimir Putin of “extremely profound” sanctions the United States would impose — the likes of which have never been seen before on an economy of Russia’s size — if Moscow follows through on its apparent threats to invade Ukraine.

President Joe Biden spoke for over two hours by video call with Putin and “could not have been clearer” in his message that the United States would punish severely any Russian incursion into Ukraine, said Victoria Nuland, undersecretary of State for political affairs.

“What we are talking about would amount to essentially isolating Russia completely from the global financial system with all of the fallout that that would entail for Russian business, for the Russian people, for their ability to work and travel and trade, and we are looking at the full suite of options,” Nuland said at a Senate Foreign Relations Committee hearing on U.S. policy toward Russia.

Biden made “crystal clear” to the Russian leader the United States would not accept his demands to take Ukrainian membership in NATO off the table as the price for ensuring that Russia doesn’t invade Ukraine, which is slightly smaller than Texas, Nuland said.

The Russian military has mobilized some 100,000 troops on Ukraine’s border and an attack could come in early 2022, said Nuland, a former career diplomat who served as assistant secretary of State for Europe during the Obama administration.

Nuland met with Foreign Relations members Monday for a classified Russia briefing where she detailed anti-Russia sanctions the administration was readying. However, citing ongoing diplomacy, she declined to detail in a public setting exactly what those sanctions would be.

But Nuland, the State Department’s fourth-ranking official, said administration officials are discussing the envisioned sanctions with allies in hopes of producing a strong multilateral sanctions response to Russia.

“Going beyond that in this open session, I think, doesn’t get from here to there,” she said in response to Sen. Ron Johnson’s request that she provide “granular detail” to the Russian people about what sanctions are being prepared.

But Senate Foreign Relations Chairman Bob Menendez touted the language he offered as an amendment to the fiscal 2022 defense policy measure as an example of the types of sanctions Congress might swiftly pass to punish Russia if it invades Ukraine.

The New Jersey Democrat said his envisioned economic penalties would ban the purchase of Russian national debt and deny it access to the SWIFT electronic payments system, which is relied on heavily by banks around the world.

“The Russian banking sector would be wiped out,” Menendez said. “Sectoral sanctions would cripple the Russian economy. Putin himself as well as his inner circle would lose access to bank accounts in the West. Russia would effectively be cut off and isolated from the international economic system.

“Let me be clear — these are not run-of-the-mill sanctions,” Menendez continued. “What is being discussed is at the maximum end of that spectrum, or as I have called it, the mother of all sanctions. And I hope that we can come together in a bipartisan way to find a legislative path forward soon so that we can achieve that.”

Multiple senators, including Foreign Relations ranking member Jim Risch, R-Idaho, Sens. Mitt Romney, R-Utah, Johnson, R-Wis., Benjamin L. Cardin, D-Md., and Chris Van Hollen, D-Md., said at the hearing they wanted to be associated with Menendez’s sanctions threat to Russia.

“Vladimir Putin should understand that there is going to be a strong, unified, severe response should he decide to invade Ukraine,” Van Hollen said, while also pressing the administration to reconsider publicly detailing the sanctions that Russia is risking. “I’m a big believer that sanctions are actually more useful and effective when you lay them out in advance and say to a foreign leader these are the consequences if you take these actions, rather than trying to reverse action after the fact through sanctions.”

One area of disagreement between lawmakers and the administration is over how forcefully to stand against the opening of the Nord Stream 2 pipeline, which would transport Russian natural gas undersea to Germany and other parts of Europe. The new pipeline would deprive Ukraine of badly needed revenue it currently receives from allowing the gas to travel through its territory into Europe.

Earlier this year, Biden exercised a congressionally provided waiver to get out of imposing sanctions otherwise required by Congress on some of the leading companies and individuals behind the pipeline. The administration struck a deal with former German Chancellor Angela Merkel’s government to try to make Kiev economically whole and safe from Russian economic coercion through other means.

Construction of Nord Stream 2 is essentially completed even as the regulatory approval process in Germany has been halted.

Nuland said if Russia attacks Ukraine, she would expect that work on Nord Stream 2 would be “suspended.”

“The fact is that gas is not currently flowing through the Nord Stream 2 pipeline,” White House national security advisor Jake Sullivan said at a briefing on the Biden-Putin call. “It is leverage for the West, because if Vladimir Putin wants to see gas flow through that pipeline, he may not want to take the risk of invading Ukraine.”

Fortifying NATO and Ukraine

The Biden administration is also making clear the United States is preparing contingencies for additional support for the territorial integrity of NATO member states.

Sullivan told reporters Washington is prepared to work on “fortifying eastern flanks” in the event of further Russian incursion into Ukraine.

Sullivan said the United States would be “looking to respond positively” to providing further capabilities to Poland and Romania. He noted that U.S. troops already operate as part of rotations in the Baltics.

Since 2014, the United States has provided over $2.5 billion in security assistance to Ukraine.

Lawmakers are expected to increase the level of annual security assistance Ukraine receives to $300 million, up from enacted levels of roughly $275 million, according to the text of the final comprise bill (S 1605) of the fiscal 2022 National Defense Authorization Act, which was released Tuesday.

“We must make it clear to the Kremlin that the U.S. will put its money where its mouth is and help Ukraine defend its territorial integrity,” Senate Foreign Relations member Jeanne Shaheen, D-N.H., said in a statement touting the increased defense funds for Ukraine that she and Sen. Rob Portman, R-Ohio., pushed to be included in the bill.

Senators and administration officials also dwelled at length on the resolve of the Ukrainian people to fight back if they are attacked again by Russia, which seized the Crimean Peninsula in 2014 and has been supporting an insurgency campaign in eastern Ukraine ever since.

“To bet against Ukrainian patriotism is very, very dangerous as a lot of Russians have found already, and unfortunately there are many, many reasons why none of us should want a war,” Nuland said. “It will be extremely bloody and difficult for Ukraine but it will also be extremely bloody and difficult for Russia and many of them will not go home as they came.”

Niels Lesniewski contributed to this report.