President Donald Trump met with Ukrainian leader Volodymyr Zelenskyy on the sidelines of the NATO summit Wednesday and suggested that increased spending by the trans-Atlantic alliance could help prevent future Russian aggression against its neighbors.

NATO members agreed to raise their spending targets by 2035 to 5% of gross domestic product annually on core defense requirements as well as defense-and security-related spending. That target had been 2% of GDP.

“Europe stepping up to take more responsibility for security will help prevent future disasters like the horrible situation with Russia and Ukraine,” Trump said at the summit-ending news conference shortly after seeing Zelenskyy. “And hopefully we’re going to get that solved.”