New Delhi, Feb. 11 -- Oil and gas exports have sustained Russia's finances throughout its war against Ukraine. But as the fourth anniversary of the full-scale invasion approaches, those cash flows have suddenly dwindled to lows not seen in years.

It's the result of new punitive measures from the U.S. and the European Union, U.S. President Donald Trump's tariff pressure against India, and a tightening crackdown on the fleet of sanctions-dodging tankers carrying Russian oil.

The drop in revenue is pushing President Vladimir Putin to borrow from Russian banks and raise taxes, keeping state finances on an even keel for now.

But those measures only increase strains in a war economy now plagued by slowing growth and stubborn inflation.

In J...