Russia has lashed out at the United States over new sanctions announced by Washington at the end of last week, calling the measures "unacceptable" and illegal and saying it reserves the right to retaliate.
In remarks on April 9, senior officials in President Vladimir Putin's government also said they were assessing the damage to Russian companies and promised state support for big Russian firms targeted by the punitive measures.
They spoke as the ruble and Russian stock indexes fell, with companies included on the U.S. sanctions list -- such as tycoon Oleg Deripaska's aluminum giant Rusal -- taking substantial hits.
Forbes magazine estimated that in total, the stocks and other investments of Russia's 50 richest people lost $12 billion in value in one day after the sanctions were imposed.
On April 6, the United States imposed asset freezes and financial restrictions on a slew of Russian security officials, politicians, and tycoons believed to have close ties to Putin -- part of an attempt to punish Moscow for what the U.S. Treasury Department called "malign activity around the globe."
The new sanctions were "glaring in their illegality," said Putin's spokesman, Dmitry Peskov, adding that Russian authorities were analyzing the potential effects on the economy. He refrained from quantifying the potential losses when asked, saying that "we are seeing the first effects" of the sanctions.
"We need time to understand the scale and work out measures to react," Peskov said.
Prime Minister Dmitry Medvedev said that the new sanctions were "unacceptable, without a doubt, and we consider them illegitimate as they are entirely outside the realm of international law."
He alleged that they were imposed to protect U.S. companies from Russian competition, warned that Moscow reserves the right to retaliate, and ordered the government to work out "specific proposals on what concrete support" the state could provide the companies targeted.
The dollar and the euro rose substantially against the ruble, hitting their highest rates since the second half of 2017, and the dollar-denominated RTS stock index was down more than 11 percent, hitting its lowest level since September 2017.
The sanctions were levied under a 2017 law passed by Congress over President Donald Trump's objections.
In January, the administration came under criticism in Congress and elsewhere for releasing an "oligarchs list" -- naming the business and political leaders who could be potentially targeted -- but not actually imposing any penalties.
In other fallout from the new sanctions, Russian aluminum giant Rusal saw its share price plummet after the company and co-owner Deripaska were targeted, prompting the producer to warn of potential debt defaults.
Rusal stock nearly halved to HK$2.39 in Hong Kong trading on April 9, while aluminum prices surged. Rusal shares were losing more than 20 percent in the Moscow stock exchange.
Trading of Deripaska's En+ Group, which manages Deripaska's assets, was temporarily halted in London after its shares lost almost one quarter of their value.
The sanctions increase the risk that Russian companies could lose access to the U.S. market -- which accounted for about 14 percent of Rusal's revenue in 2017, Reuters quoted analysts at Russia's Promsvyazbank as saying.
In a sign that Russian companies could also see investment partners withdraw to reduce their risks, Swiss engineering company Sulzer decided to buy back 5 million of its own shares from majority shareholder Renova Group after an emergency board meeting on April 8, Reuters reported.
Viktor Vekselberg, a prominent Russian tycoon who is Renova's chairman, was included on the sanctions list.
Deputy Prime Minister Arkady Dvorkovich, one of several officials who suggested the state would step up support for Russian companies hit by the sanctions, portrayed them as a blow to ordinary workers -- not just tycoons like Deripaska.
"Support for these companies is being provided on a consistent basis. We are very attentive toward our leading companies -- these are thousands-strong collectives that are very important to our country," Dvorkovich told journalists when asked about the issue.
"But in the current situation, as their situation deteriorates, we will provide this support."
Rusal said the sanctions may result in technical defaults on some credit obligations and be "materially adverse to the business and prospects of the group," casting a cloud over its future performance.
Rusal is the biggest aluminum maker outside China, accounting for some 7 percent of the world's production.
Deripaska has called the U.S. decision to impose sanctions on him "groundless, ridiculous, and absurd."
Earlier on April 9, Foreign Ministry spokeswoman Maria Zakharova said Moscow was considering how to respond.
"We have a whole list of possible measures that are being studied," Zakharova said.
Asked whether the Russian response would be harsh, Zakharova said that she "would rather not jump the gun."
"We are considering our countermeasures, as we always do," she said.