(NewsNation) — Just days after Russian President Vladimir Putin’s army invaded Ukraine, President Joe Biden and U.S. allies weaponized the global financial system against Russia, laying economic siege to Putin’s country. And experts say there could be more to come.

“If you think of sanctions on a continuum of 0 to 100, where 100 is the maximum amount of sanctions pressure you can impose on a country … Russia is probably at 65-70%, whereas Iran is closer to 95%,” said Brian O’Toole with the Atlantic Council’s GeoEconomics Center, who specializes in economics and national security.

Although countries including Iran and North Korea have faced worse sanctions before, O’Toole said the size of Russia’s economy means the current sanctions are likely more impactful than anything previously imposed, but there’s still plenty that can be done.

So far, the U.S. and its allies have sanctioned Russia’s largest financial institutions, downgraded the country’s trade status, blocked luxury goods exports and even gone after some of the wealthiest people in Putin’s inner circle.

Russian planes can no longer enter U.S. airspace, and vodka and other Russian imports such as seafood have also been banned.

The U.S. and Britain have blocked Russian oil imports, targeting the lifeblood of Russia’s energy sector. Over the past month, the Russian ruble has lost about half of its value against the U.S. dollar.

On Wednesday, Ukrainian President Volodymyr Zelenskyy gave an impassioned speech before Congress, calling for additional sanctions against Russia.

So what other sanctions could Biden impose?

option 1: sanction more russian companies

Although the Biden Administration has sanctioned Russia’s two largest financial institutions, Sberbank and VTB bank, other banks such as Alfa-Bank have not faced the same level of sanctions. State-owned companies in Russia’s rail sector and insurance industry have also been spared the worst of Biden’s sanctions.

“There are a whole bunch of companies in Russia that are big major companies that have yet to be sanctioned. Those include private banks, like Alfa-Bank or others, as well as Russian railways, or the insurance sector with a company like Sogaz, which the EU has (sanctioned) but the U.S. hasn’t,” said O’Toole.

So how likely is it that more Russian companies face the full brunt of U.S. sanctions? O’Toole said many of the financial institutions that avoided earlier restrictions could be on the chopping block soon, pointing out that it would be relatively easy to add them to the list.

option 2: sanction russian stock markets

Stock trading on the Moscow Exchange has been closed since Feb. 25 but the U.S. could aim sanctions at the stock market when it reopens. Doing so would dramatically reduce the amount of capital available to fund trades, which could cause further turmoil for the ruble and Russian credit.

Sanctioning the stock market would also deter companies outside of Russia from capitalizing on the current turmoil, buying assets on the cheap and profiting later on, something O’Toole said is a concern.

“Vulture funds are famous for swooping in when assets are depressed and hoping that they can get a return out of them, even if there’s risk,” he said.

OPTION 3: SANCTION MORE OLIGARCHS

The Biden administration has sanctioned a number of Russian oligarchs, targeting the assets of Putin’s ultrawealthy allies and blocking them from travel to the U.S. However, there are many that have not been sanctioned, or have been sanctioned only partially.

Chelsea FC owner Roman Abramovich was not included on the list of “Putin’s cronies” released by the White House earlier this month, despite numerous European countries targeting the billionaire. Others absent from Biden’s list were Mikhail Fridman and Petr Aven; both face sanctions from the European Union.

Overall, O’Toole thinks the sanctions against Russian oligarchs have less of an impact than other measures targeting financial institutions.

“Seizing a yacht is flashy but even a $600 million yacht doesn’t do the same damage as undermining the banking sector,” said O’Toole.

Even if the U.S. chose to target more oligarchs, O’Toole said it’s hard to know just how much impact they have over Putin and whether that influence could change the course of the war.

OPTION 4: FULL FINANCIAL EMBARGO

On the extreme end of the spectrum, the United States could cut off trade with Russia entirely. A full embargo would prohibit all services, technologies and goods from being exported to or imported from Russia.

The Biden administration has cut off some Russian imports already, including oil, vodka, seafood and diamonds, but other goods and natural resources continue to enter the country.

The U.S. and its allies have also stripped Russia of its most-favored-nation trade status, which allows them to impose significant tariffs on some Russian goods.

All of that falls short of a full financial embargo, which O’Toole said would be the most significant economic action the U.S. could take.

“Broadly speaking, that would make it so that no business or person in Russia could transact with the United States,” said O’Toole.