Around this time of year, Yaroslav Andrushko would normally be overseeing the sowing of crops on his 1,000-hectare farm in the Vinnytsya region of central Ukraine.

Instead, he swapped his workwear for fatigues, joining the army a day after Russia invaded his country. "Once a farmer always a farmer,” said Andrushko, the chief executive of a small agriculture company. "But circumstances required us to take up arms.”

As Ukrainians resist Russian President Vladimir Putin’s military machine, the 36-year-old is another example of the resilience shown by so many of his compatriots in protecting their nation’s statehood. Yet Andrushko and farmers like him are also defending a core component of the global food supply chain that’s increasingly in peril.