President Obama’s most recent visit to Asia probably struck many Americans as simply the latest round of executive-level diplomacy – basically the kind of trip abroad that chief executives have been making for decades. He’s been to the region six times as president, after all – not much different than President Bush at a comparable point in his presidency.

There was more to it than that, though. The unstated mission seemed to be to reassure our nervous allies that we remain committed to their security, and that we’re ready, willing and able to defend them against escalating threats.

Unfortunately, it’s not hard to see why our allies and friends in Japan, South Korea, Malaysia and the Philippines – the four countries the president visited – would need such a message.

For one thing, China has been aggressively asserting its sovereignty, using its military to try to enforce specious claims to territory throughout the East China Sea and South China Sea. This explains why, for example, Mr. Obama made a point of saying that the Senkaku Islands fall under the defense treaty between the United States and Japan.

“Let me reiterate that our treaty commitment to Japan’s security is absolute, and Article 5 [of the bilateral security treaty] covers all territories under Japan’s administration, including the Senkaku Islands,” the president said during a news conference with Japanese Prime Minister Shinzo Abe.

Though this marked the first time a president had expressly pointed out that the treaty covers the islands, it was hardly a new message. During a flare-up of tensions between China and Japan over the Senkakus in 2010, then-Secretary of State Hillary Clinton noted that the islands “are part of our mutual treaty obligations.” In 2004, former Deputy Secretary of State Richard Armitage made the same point.

Yet it was necessary to say it again. Mr. Obama also gave clear public statements in support of our treaty commitments to the Philippines (forging a deal that will result in a greater U.S. military presence at Philippine bases), and signed up Malaysia to a Bush-era program known as the Proliferation Security Initiative.

It’s not just China’s latest round of bellicose behavior that led to such reassurances. Troubling cuts in the U.S. defense budget, especially in the wake of last year’s “sequestration,” haven’t gone unnoticed by our allies. They can count warships and bombs as easily as the rest of us, and they aren’t happy about what they’re seeing.

“Well before sequestration,” writes Asia expert Bruce Klingner, “it was clear that the administration was underfunding defense requirements in a way that would undercut its commitments.”

He points out the fact that the Navy’s shipbuilding budget has been too low for years, resulting in fewer vessels than we need to fulfill our obligations in Asia and elsewhere. Gen. John M. Paxton Jr., assistant commandant of the Marine Corps, asked in a recent speech: “Do we have enough people and enough ships to do it?” The answer was clearly no.

“The ‘Asia Pivot’ or ‘rebalance’ has always been more hype than reality,” Mr. Klinger adds. “The policy is a sound one only if sufficient resources are devoted to deploy the requisite military forces in the Pacific.”

So if reassurances were needed, the Obama administration has itself to blame. The most successful part of the trip – soothing our worried allies – shouldn’t have been necessary.

The trip wasn’t solely about security, however. It was also supposed to be about free trade. The president, however, failed to get an agreement with Japan on the Trans-Pacific Partnership, which is meant to expand trade in the Asia-Pacific region. Expanding economic freedom there and elsewhere requires strong presidential leadership, but his track record on this issue isn’t nearly good enough.

Mr. Obama is good at campaigning, though, and that’s exactly what his administration’s “the U.S. is back in Asia” sounds like – feel-good sloganeering. The fact is, the United States never left Asia.

However, unless we fully fund our defense commitments and get serious about promoting economic freedom, we might as well have. Doing those things, though, takes true leadership. Right now, our allies in Asia aren’t the only ones who need reassurances on that score.