U.S. Secretary of State Marco Rubio on Saturday blasted the idea of a "world without borders," warning European leaders that unchecked mass migration is destabilizing Western civilization and eroding national sovereignty.

Speaking at the annual Munich Security Conference, Rubio criticized the post-Cold War belief that the world had reached the "end of history" — an era in which liberal democracy would spread, and national borders would fade — calling it a "dangerous delusion."

"This was a foolish idea that ignored both human nature, and it ignored the lessons of over 5000 years of recorded human history, and it has cost us dearly," Rubio said.

Rubio stressed that border security is not rooted in exclusion, but in responsibility.

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"We must also gain control of our national borders, controlling who and how many people enter our countries," he said. "This is not an expression of xenophobia. It is not hate. It is a fundamental act of national sovereignty."

Failing to do so, Rubio warned, is "not just an abdication of one of our most basic duties owed to our people — it is an urgent threat to the fabric of our societies and the survival of our civilization itself."

The U.S. top diplomat added that lax enforcement threatens "the cohesion of our societies, the continuity of our culture, and the future of our people."

Rubio’s remarks come amid mounting political tensions in both Europe and the U.S. over migration, asylum policy and border security.

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Outlining America’s direction under President Donald Trump, Rubio said the U.S. seeks to rebuild its alliance with Europe on stronger footing.

"We want allies who can defend themselves so that no adversary will ever be tempted to test our collective strength," he said. "This is why we do not want our allies to be shackled by guilt and shame. We want allies who are proud of their culture and of their heritage, who understand that we are heirs to the same great and noble civilization, and who, together with us, are willing and able to defend it."

"We in America have no interest in being polite and orderly caretakers of the West's managed decline," Rubio said. "We do not seek to separate, but to revitalize an old friendship and renew the greatest civilization in human history."

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The secretary said the U.S. seeks an alliance "ready to defend our people, to safeguard our interests, and to preserve the freedom of action that allows us to shape our own destiny, not one that exists to operate a global welfare state and atone for the purported sins of past generations."

Rubio reminded attendees that America’s ties to Europe stretch back centuries, saying the U.S. will remain permanently linked to the continent.

"What we have inherited together is something that is unique and distinctive and irreplaceable," Rubio said. "Acting together in this way, we will not just help recover a sane foreign policy, it will restore to us a clear sense of ourselves. It will restore a place in the world, and in so doing, it will rebuke and deter the forces of civilizational erasure that today menace both America and Europe alike."

Marco Rubio could not be immediately reached by Fox News Digital for comment.