Since the conclusion of the final round of nuclear negotiations, Iran has been engaging in conspicuous displays of aggression.

The U.S. Navy revealed on Tuesday that four Iranian Revolutionary Guards ships intercepted a Maersk cargo vessel in the Strait of Hormuz that was flying a U.S. flag. The episode happened last week and ended without incident, but it was only revealed to the press after Iranian naval vessels performed a similar act of belligerence on Tuesday.

Yesterday, another Maersk container ship, the Tigris, was intercepted by Iranian vessels in international waters, according to the firm. Iranian ships fired over the bow of the Tigris, boarded it, and forced it to proceed to an Iranian port. Shortly after the ship was fired upon, it issued a distress signal that was picked up by a U.S. guided-missile destroyer, the USS Farragut. American warplanes were then tasked with tracking the Maersk vessel as it was forcibly guided into Iranian territorial waters.

The ship was originally reported by the Saudi-owned news agency al-Arabiya to be an American craft, and a few surely breathed a sigh of relief when they learned that the ship was actually flying a Marshal Islands flag. That relief was short lived.

“The Marshall Islands signed a Compact of Free Association with the United States in 1983 and gained independence in 1986 with the Compact’s entry into force,” read a State Department fact sheet on the status of America’s bilateral relations with the former Japanese territory. “The United States has full authority and responsibility for security and defense of the Marshall Islands, and the Government of the Marshall Islands is obligated to refrain from taking actions that would be incompatible with these security and defense responsibilities.”

By mid-afternoon on Tuesday, it appeared as though Iran had ignited an international incident. Moreover, it seemed that the Islamic Republic had possibly triggered America’s obligations by treaty to come to the tiny island nation’s defense. “When asked if his country would request that the U.S. rescue the cargo ship from Iran, Junior Aini, the charge d’affairs for the Marshall Islands Embassy in Washington, told us he was still awaiting guidance from his foreign ministry,” Bloomberg’s Eli Lake and Josh Rogin reported. “But he also suggested that his country had no other recourse than to hope the U.S. responds.”

But a Pentagon statement released shortly after the Tigris was intercepted contradicted observers who, using public technology, discovered that the ship was in international waters when it was boarded by Iranian forces. The Secretary of Defense’s office insisted that the Maersk vessel was diverted “while in Iranian territorial waters transiting inbound in the Strait of Hormuz.” Moreover, upon consultation with the Pentagon’s legal team, it seems as though the United States actually has no obligation to abide by its treaty obligations with the Marshall Islands. How convenient!

.@CBSDavidMartin "Pentagon lawyers have determined..US has no obligation to come to the defense of a Marshall Islands-flagged vessel at sea"

— Major Garrett (@MajorCBS) April 28, 2015

The Iranians have reportedly released this Maersk ship, but this was merely the latest episode in what is becoming a disturbing pattern of behavior. The Tigris is unlikely to be the last boat seized by Iranian forces. And the world surely took notice when the United States, while certainly working behind the scenes on the Marshall Islands’ behalf, found it counterproductive to vocally defend their ally and threaten the use of retaliatory force in order to defend their sovereign interests.

There is no better metric to measure the health of American hegemony than whether trade ships enjoy unfettered access to sea lanes. Global maritime law is among the more settled concepts in international law, and its violation has universally understood consequences. American naval power guarantees the right of safe passage, and hostile powers know that they will encounter resistance if they used military force to prevent commercial ships from proceeding along their routes. At least, they knew that until Tuesday. Today, the world awakes to a new reality in which the United States has blinked.

If you’re watching affairs from Moscow, or Beijing, or Tehran, or the capital of any other revisionist power, why wouldn’t you believe that America’s alliances are barely worth the paper on which they are written? Why wouldn’t the Kremlin think it could test NATO’s commitment to the defense of Eastern European states. Would London, Paris, Berlin, and Washington really risk war with a nuclear power over a sliver of territory in eastern Estonia? It no longer seems like much of a risk to find out. Similarly, why would the People’s Republic of China believe that a flotilla of “fisherman” colonialists who establish a base on the contested Senkaku Islands would be resisted with force? There is simply no evidence to suggest that would be the case. At least, not under this administration.

It’s a more dangerous world today, and much of that is a result of Barack Obama’s repeated displays of impotence and irresoluteness. Before this week, when it comes to America’s obligations to its allies, Obama’s “you’re on your own” doctrine was only perceived. Today, it’s precedent.