This week’s NATO leaders meeting marks the 70th anniversary of NATO, the strongest and most effective political-military alliance in modern history. Throughout its existence, the alliance has prevented another war on the European continent, advanced America’s safety and security, and provided the foundation for unprecedented prosperity on both sides of the Atlantic. It has furthered the aims of free societies everywhere.

American leadership has served as the backbone of NATO since its founding — until President Trump. His abdication of America’s traditional leadership role could not come at a more critical moment for the alliance. Russia continues to intimidate our European allies, undermine transatlantic unity, take aggressive actions against countries like Ukraine, and interfere in the democratic processes of NATO member states. Meanwhile, authoritarian governments are resurgent around the world and are taking advantage of democratic backsliding within NATO’s ranks.

NATO’s ability to remain the world’s strongest alliance — and to act collectively in the face of security threats — depends on shared values, trust, and cohesion. The failure of American leadership and rising authoritarianism, even among some NATO members, threaten these critical pillars of NATO.

As President, I will call for a review of NATO members’ democratic commitments. I will also work with our allies to draft a new strategic concept for NATO that acknowledges the challenges of Russian aggression, democratic backsliding within NATO, and disruptive technologies like artificial intelligence. At NATO summits and in bilateral engagements, a Biden presidency will prioritize strengthening national democratic institutions in member states that are not living up to NATO’s core values. Democratic and free institutions are the bedrock of our alliance, and they must be defended to strengthen our collective security.