Few factories make the tubes, valued for the sound quality they bring to amplifiers. A run on the market is driving up prices.
Investing in Russian debt while it's cheap can pay dividends but comes with uncertainty and reputation risk.
Russia supplies more of the EU's oil and gas than it does coal.
The Biden administration is considering secondary sanctions on Russia – and its supporters.
Probably not, but Russia and China are likely to keep looking for ways to avoid U.S.-controlled financial infrastructure.
The Chinese government is opposed to sanctions against Russia and says it will continue to trade with it. But that is not easy in practice.
The U.S. could expand tariffs on Chinese goods — but that may raise prices for American consumers.
"The long-term implications are severe," one expert says, and can scare away foreign investors.
Russia's economy relies on imported tech, like aircraft parts and semiconductors. That leaves it vulnerable as sanctions multiply.
Biden's ban on Russian oil may raise already high fuel prices. Though recessions followed past runups, this time may be different.