Dutch Prime Minister Mark Rutte said Thursday it was imperative that Europe continued to stand up to Russia’s aggression, saying the region had to do “everything we can to help Ukrainians.”

“If an aggressor is not challenged and can go about his business, it won’t end with Ukraine. The whole West is threatened,” Rutte told CNBC, as he discussed Europe’s response to the war in Ukriane at the World Economic Forum in Davos.

Rutte referenced the 1938 Munich Agreement in his discussion with CNBC’s Steve Sedgwick, where the allied forces agreed that Czechoslovakia would surrender its border regions and defenses to Nazi Germany.

“People feel that this is about values, that we cannot accept one country invading another country … It is also about our collective safety,” he added.

Rutte also said Europe needs to do more to help Ukraine, but that the issue of sending tanks is “a sensitive decision.”