Vladimir Putin has no intention of stopping at Ukraine, and his victory there would mean war against NATO, according to former head of the US Central Intelligence Agency (CIA) David Petraeus.

Western allies of Ukraine must do more to win the war with Russia, as Putin has "made it very clear" that he wants to bring another war to Europe.

"The war in Ukraine could spread to the region if Putin succeeds in Ukraine. Moldova will obviously be next. After that, it could be Lithuania or one of the other Baltic states," Petraeus said.

Separately, Petraeus noted that one of the levers that will help Ukraine defeat Russia is the development of its own technologies.

"Remember that what they did in the Black Sea was not done by their ships or sailors, but by their unmanned aerial vehicles. Naval drones, aerial drones, and anti-ship missiles allowed them to sink a third of the ships of the Black Sea Fleet," the former head of the CIA emphasized.

However, according to Petraeus, the key to winning the war is for Ukraine to quickly increase its numbers and military power — with the help of its Western allies.

"The reality is complex, and this is another reason why we should do everything possible to help Ukraine in every possible way," he concluded.