The United States and European countries continue to pledge their support to Ukraine as Russia’s invasion drags on into its ninth month – and have backed their alliance with recurrent deliveries of advanced weaponry and money.

But despite Russian President Vladimir Putin’s threats to Western powers of nuclear strikes, neither the U.S. nor any Western European country, unified under the military coalition NATO, has actually declared it is part of the war.

The U.S. has provided US$17.6 billion in security assistance to Ukraine since Russia first invaded Ukraine in February 2022. But it can be difficult to track foreign aid and to distinguish between money that governments have promised and actually delivered. Some unofficial estimates place U.S. commitments to Ukraine made in 2022 much higher, at $40 billion.

European countries, meanwhile, have collectively donated an estimated 29 billion euros – or more than $28.3 billion – in security, financial and humanitarian aid in 2022 – not including additional aid to Ukrainian refugees.

This support has made it possible for Ukraine to fend off a Russian conquest of the country. Without Western aid, equipment and training, Ukraine would likely have already suffered defeat to the Russian incursion.

As a scholar of war and military interventions, I think the situation in Ukraine represents a classic case of a proxy war, in which outsiders give allies money, weapons and other kinds of support – but not at the risk of their own soldiers’ or civilians’ lives.

A better understanding of what proxy wars actually are, and what purpose they serve, provides useful context for the the U.S. and NATO’s current unofficial involvement in the Ukraine war.

What proxy wars are

Proxy wars are armed conflicts in which one nation sends resources other than its own military personnel – like weapons, trainers, advisers, surveillance drones, money or even mercenaries – to support another country fighting in a war. This is often done to achieve a political objective, like regime change in another country.