Speaking at the United Nations on Tuesday, President Donald Trump delivered one of the most powerful speeches of his presidency thus far.

The speech was an emphatic rejection of President Barack Obama’s “leading from behind” mantra, giving an assertive defense of American leadership on the world stage. The president also delivered strong condemnations of an array of dictatorial regimes, including North Korea, Iran, Venezuela, and Cuba.

The speech could not have been more different in style and substance than Obama’s weak-kneed and deferential approach in past speeches to the U.N. Obama’s tenure as leader of the free world was marked by weakness, confusion, indecision, and at times outright appeasement of U.S. adversaries.

It was refreshing to hear a U.S. president who was not ashamed to proclaim the interests of his own country.

The U.N. General Assembly is traditionally a lion’s den for Republican U.S. presidents, but Trump showed no desire to temper his message before leaders from 193 countries, many of whom harbor a deep-seated antipathy for the United States.

Global leadership is not a popularity contest, and Trump showed little interest in winning applause from a General Assembly that had regularly regaled his predecessor with standing ovations.

This was a speech that was tough, uncompromising, and crystal clear in its messaging. The enemies of the United States will be left with no doubt that the United States will aggressively confront them and halt their ambitions to threaten the free world.

In particular, the president targeted North Korea and Iran. He delivered the Iranian regime the heaviest fire it has received in many years, making clear that he views Iran as a “rogue nation” and the nuclear deal signed by Obama as an “embarrassment.”

Trump’s speech was the clearest indication yet that he may walk away from the failed Joint Comprehensive Plan of Action, which is currently subject to a review by the Trump administration.

In marked contrast to the supranationalist approach of the Obama administration, Trump’s speech celebrated sovereignty and self-determination. It came as a rallying cry in defense of the nation-state and a rejection of the notion that national sovereignty should be weakened or surrendered.

Coming in the wake of Brexit, Trump’s remarks in New York are a reminder that the defense of sovereignty is fundamental to the protection of liberty and freedom.

That is a message that should be heeded not only at the U.N., but also in Brussels, where the European Commission is recklessly driving forward with plans for an increasingly centralized federal Europe that would diminish national sovereignty.

As president, Obama spent much of his time on the world stage apologizing for his own country and seeking to accommodate the enemies of the free world. After eight years of dangerous global retreat, Trump demonstrated on Tuesday that American leadership really does matter and that he will confront dictatorial regimes that threaten global security.

At a time when the U.S. and its allies face mounting threats, this is exactly the right message to send.