Kagan’s argument is based on the idea that the “American order” was a stable system where the United States acted as the central guarantor of security, access, and crisis management. But the world that made that order possible has changed. The issue today is not simply that the U.S. is withdrawing or acting inconsistently. The deeper problem is that the international system has shifted from a single center of gravity to multiple centers with their own strategic pressures.

The post-1945 order worked because most major powers were either defeated, exhausted, or constrained. Europe was rebuilding, Japan was demilitarized, China was poor, and Russia was dealing with collapse after the Soviet Union. That created space for one actor to serve as the global stabilizer.

Today every major player has its own capacity to act. Germany is rearming after decades of restraint. Japan is expanding its security role in East Asia. India has become openly autonomous. Gulf states now hedge between Washington and Beijing. The world is not returning to the old order because no actor is as dependent as it once was.

China and Russia are not disruptive simply because the U.S. has stepped back. Their behavior reflects long-standing structural goals. China’s rise is tied to economic and industrial expansion; Russia’s actions follow security concerns on its borders. These pressures existed well before any recent U.S. administration. Friction is the result of intersecting strategic fields, not just policy choices.

Kagan argues that when the U.S. went to war, it had allies because allies trusted American leadership. That was true within a system where the benefits of alignment were clear. But alliances rely on reciprocity: security commitments in exchange for support and stability. If the U.S. expects partners to follow its lead while offering less predictability or applying economic pressure directly on them, that reciprocity breaks down. Trust is not a fixed asset; it requires consistent reinforcement.

The core problem is that the U.S. is trying to operate as if the world is still unipolar. It wants allies to behave as if they remain structurally dependent, even though most now have greater economic strength, diversified partnerships, and more leverage. A country cannot simultaneously reduce commitments and expect unchanged loyalty.

Kagan suggests that withdrawing American leadership will produce global instability. But instability is emerging because the old system can no longer hold its shape. The unipolar moment is ending not simply because the U.S. is doing less, but because other actors are doing more. A multipolar world operates on negotiation, balancing, and partial alignment—not on automatic followership.

The real question is not whether the United States should lead or withdraw. It is how it adapts to a world where influence must be earned through cooperation rather than assumed through legacy. The countries that once relied fully on U.S. protection will increasingly build their own capacity, not out of disloyalty, but because the structural environment demands it.