He told LBC about this.
When asked why Britain cannot shoot down drones over Ukraine, Cameron said that this would mean bringing NATO forces into direct conflict with Russian troops and lead to an "escalation."
"I think the difficulty with what you suggest is if you want to avoid an escalation in terms of a wider European war, I think the one thing you do need to avoid is NATO troops directly engaging Russian troops. That would be a danger of escalation," Cameron said.
He believes that the best thing the UK and other countries can do is to continue to provide financial support to Kyiv.
"We've done more than any other country individually to help the Ukrainians. We've trained over 60,000 Ukrainian troops, we were the first to give them anti-tank weapons, long-range artillery and tanks," Cameron said.
According to the British Foreign Secretary, Ukraine has a greater need for access to "air defence systems", in particular the Patriot system.
"Do everything you can to support Ukraine, in terms of money, in terms of diplomacy and, crucially, in terms of weapons. Giving them weapons to defend themselves, training their troops, those things are absolutely the right thing to do," the former British prime minister said.