On his march to the White House, Donald Trump pledged to rein in China’s aggressive territorial expansion in the South China Sea. But now, more than 100 days into his presidency, there’s clear evidence that the administration hasn’t walked the walk.

In recent years, China has been using its expanding naval presence and the construction of artificial islands to make ever-bolder claims to territory in the South China Sea that has previously been considered international or claimed by countries in Southeast Asia. Some of the islands have runways that can accommodate jumbo jets and appear to have anti-aircraft guns and missile defense systems on them.

The Obama administration occasionally sent US Navy vessels through the South China Sea in deliberate violation of Beijing’s self-proclaimed rights to the area. These so-called “freedom of navigation” exercises sent a clear message to China: We don’t accept your claims to this area.

But Obama was heavily criticized for not doing this often enough, and thus not being “tough” enough on China. Trump promised to change that. During his confirmation hearing, Secretary of State Rex Tillerson implied that the US might even pursue a blockade against China in the South China Sea — an act that Chinese state media interpreted as an invitation to war.

But so far, not only has the Trump administration not been more confrontational in challenging China in the South China Sea like they promised — they haven’t even been as aggressive as the Obama administration was.

According to a New York Times report, top Pentagon officials in the Trump administration have denied three requests by the Navy to sail within 12 nautical miles of a reef in the South China Sea that both China and the Philippines lay claim to. That seems to be part of a wider trend: Defense Department officials told the Times that no Navy ship has gone within that distance of any island in the area.

Though it’s not clear if the rejections came from Defense Secretary Jim Mattis or Chair of the Joint Chiefs Gen. Joseph Dunford Jr. — or from one of their deputies — the decision not to challenge China’s territorial claims in the South China Sea fits a broader pattern of Trump reversing himself on a host of combative policy ideas on China.

Trump threatened he would decline to honor the “One China” policy that has underpinned US-Chinese diplomatic relations for decades. He didn’t. He promised to label China a currency manipulator on his first day of office. He didn’t. He said he would slap 45 percent tariffs on Chines goods to protect American workers from the “rape” of Chinese industry. So far, he hasn’t.

The most salient reason for all these walk-backs is North Korea. The country’s recent ballistic missile tests and hints that a nuclear test is imminent have put the global community on edge, and made halting North Korea’s nuclear ambitions the biggest priority of Trump’s national security agenda.

Unless Trump wants to do something as recklessly risky as strike North Korea preventively or preemptively, he’ll need China to be involved in a solution. And he believes cultivating goodwill with China is the best way to persuade it to lean harder on North Korea. China is North Korea’s economic lifeline: If it cuts off oil to North Korea or dramatically reduces trade with it, it would cripple the country’s economy, which is currently growing despite the burden of international sanctions.

None of this means that Trump will always be bashful in the South China Sea. Trump’s nominee for US ambassador to China, for example, just took a hard line on the issue during his confirmation hearing on Tuesday. "China cannot be allowed to use its artificial islands to coerce its neighbors or limit freedom of navigation or overflight," he said, echoing statements we heard in the earlier Trump days.

But on this matter — as with so many other things — it’s more important to pay attention to what the administration actually does rather than what it says.