WARS are won and lost on battlefields. But public finance plays a critical role in determining what the combatants can afford. This is particularly true for a long war, which is what Russia’s full-scale invasion of Ukraine has already become.

By declining to include funding for Ukraine as part of the recent deal to avert a government shutdown, the US Congress sent a signal of encouragement to Russian President Vladimir Putin. Meanwhile, the increase in global oil prices – now above US$90 per barrel – since July is providing new revenues for Russia’s war effort and a further psychological boost for the Kremlin.

To turn the tide back in favour of Ukraine, Congress needs to restore funding, a move supported by the Senate’s Democratic and Republican leaders, Chuck Schumer and Mitch McConnell, respectively. In addition, and just as important, the US must take further steps to reduce Russia’s oil revenues.