WASHINGTON — President Trump on Wednesday boasted that nearly 10 months of his “America First’’ foreign policy has restored strength and respect to the United States on the world stage after years of what he deemed failed leadership under his predecessors.

Hours after returning home from a 12-day, five-country excursion to Asia with few concrete announcements, Trump nonetheless declared the trip a success in uniting the world against North Korea and insisting on reciprocal trade from Asian nations.

“America’s renewed confidence and standing in the world has never been stronger than it is right now,’’ he said. “This is exactly what the world saw: a strong, proud, and confident America.’’

Announced with little notice and delivered in the early afternoon from the Diplomatic Room of the White House, the president’s speech was designed to offer a sweeping and positive assessment of his own performance as the nation’s commander in chief and top diplomat.

“America is back,’’ he said.

That assertion flies in the face of critics who say Trump has abandoned the United States’ status as a global superpower by retreating from trade agreements and backing out of the Paris climate accord. The president’s political rivals accuse him of straining relationships with allies in NATO and elsewhere while embracing despots, including President Vladimir V. Putin of Russia.

But Trump used his Wednesday speech to rebut that charge, noting his efforts to rally Arab nations to fight terror financing during a trip to Riyadh, Saudi Arabia, in the spring.

The president boasts his tough talk with NATO allies has led those longtime partners to increase their commitments to the common defense of the alliance, a demand that Trump had been making since he was a candidate.

In talking about his own foreign policy achievements, Trump has often bragged about the personal relationships he has forged with his counterparts in China, the Middle East, and elsewhere.

But in Wednesday’s speech, Trump tried to highlight what his advisers believe were three successes during the just-concluded trip to South Korea, Japan, China, Vietnam, and the Philippines: uniting opposition to North Korea’s nuclear ambitions; strengthening economic alliances; and insisting on fair trade.

Critics of Trump’s foreign policy have hammered him on all of those fronts.

They argue that the president’s use of childish names for Kim Jong Un, the North Korean leader, has deepened the possibility of a nuclear crisis, not reduced tensions. And they say Trump’s retreat from the Trans-Pacific Partnership trade agreement has robbed the United States of influence in the region.

In fact, Trump ended his Asia trip without appearing to conclude any of the one-on-one trade deals with individual nations that he often said would be the hallmark of his administration.

Despite that, Trump hoped to use the midafternoon speech to galvanize public opinion behind the idea that his leadership on foreign policy is restoring a new sense of optimism about the United States around the world.