Watching President Trump and Filipino President Rodrigo Duterte on news shows all day Sunday, wearing matching shirts, shaking hands and clinking champagne glasses at a dinner honoring South Eastern Asian nations, I became curious.

It was a cool look, and appropriate for the hot climate. But what was the significance?

The leaders' collared, ivory-hued button-downs are Barong Tagalogs. The top is a traditional Filipino men's shirt fashioned from lightweight natural fibers indigenous to the Philippines, like pineapples or bananas. The Barong's history can be traced back to the 15th century, the early days of the Spanish colonial era. Back then, the Spaniards forced indigenous Filipinos to wear the blousy shirts untucked, so as not to be confused with the ruling class.

In the 1950s, former Filipino President Ramón Magsaysay made the shirts fashionable when he wore one to his inauguration and to his subsequent private and public events. These days, Barongs are worn to very special occasions, as tuxedos are here.

Trump isn't the first president to wear a Barong when in the Southeast Asia. Bill Clinton, George H.W. Bush, and George W. Bush have all worn them out of respect. In 2015, Barack Obama wore one fashioned from the fibers of pineapples on the red carpet at the Asia-Pacific Economic Cooperation summit in Manila.

When heads of state take the time to dress like the world leader they are visiting, it's a sign that they "are trying to make a connection," said Clare Sauro, curator of  Drexel University's historic costume collection. "You are trying to establish solidarity, and friendship and belonging."

"Clothing is the great signifier," Sauro said. "It's a way of sending a message quickly to everyone."

But astute followers of politics may glean another, more troubling message from Trump and Duterte's twinning moment.

Last year, then-president Obama turned down an invitation to visit the Philippines  after the just-elected Filipino president referred to Obama as "the son of a whore." The Obama administration questioned the country's human right's practices, which activists say left thousands dead.

Of course, no one is accusing Trump of murder. But the Trump and Duterte seem to be cut from the same political cloth — one that leans toward dictatorship. Both men are firebrands who have reputations for unsportsmanlike behavior.

And there's the fact that Trump's entire trip to Asia has been rife with extracurricular political drama, most notably Trump's continued criticism of the U.S. intelligence in relation to the ongoing Russia probe. It makes one wonder, where do Trump's  allegiances lie?

So while the matching attire Trump chose for his visit to the Philippines may have been completely appropriate, it's clear to me that his Barong was more than a sartorial sign of respect for a fellow statesman.