Update (1:47 pm ET): We noted earlier that there's reason to believe that Trump's latest round of border-closure threats might be more than just presidential bluster. And now, it appears the market agrees.

The Mexican peso has tumbled to session lows as traders have slowly come to the conclusion that Trump might be serious about shuttering the border next week to try and send a message to the Mexican government. After tweeting the threat earlier today, Trump said Friday afternoon that he might keep the border closed for a long time.

Sounding angry and fed up, Pres Trump says Mexico has to stop illegal crossings into the US. If it doesn't, he says he'll shut the southern border for a long time. Also calls on Guatemala, Honduras, El Salvador & Colombia to do more to stop caravans and drugs headed for US. pic.twitter.com/HkFALvqvMV — Mark Knoller (@markknoller) March 29, 2019

And down it goes...

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In the past, when President Trump threatened to close the southern border over Mexico's unwillingness to crack down on illegal immigrants crossing through its territory, many took his words with a grain of salt. But after the president twice tried to dictate federal policy via tweet over the past week, there's cause to believe this might be more than just frustrated presidential bluster.

For the second time in as many days, President Trump has threatened to close the southern border if Mexico doesn't take action to "stop illegals from entering the US". The tweets follows reports that "the mother of all caravans" has been forming in Honduras, with as many as 20,000 people hoping to eventually cross into US territory.

Meanwhile, another caravan of 2,500 Central Americans and Cubans has been slowly making its way through Mexico, though they have encountered a cooler response from locals and authorities than what greeted previous caravans.

The DEMOCRATS have given us the weakest immigration laws anywhere in the World. Mexico has the strongest, & they make more than $100 Billion a year on the U.S. Therefore, CONGRESS MUST CHANGE OUR WEAK IMMIGRATION LAWS NOW, & Mexico must stop illegals from entering the U.S.... — Donald J. Trump (@realDonaldTrump) March 29, 2019

....through their country and our Southern Border. Mexico has for many years made a fortune off of the U.S., far greater than Border Costs. If Mexico doesn’t immediately stop ALL illegal immigration coming into the United States throug our Southern Border, I will be CLOSING..... — Donald J. Trump (@realDonaldTrump) March 29, 2019

....the Border, or large sections of the Border, next week. This would be so easy for Mexico to do, but they just take our money and “talk.” Besides, we lose so much money with them, especially when you add in drug trafficking etc.), that the Border closing would be a good thing! — Donald J. Trump (@realDonaldTrump) March 29, 2019

Can Trump's advisors dissuade him from taking such a drastic step, which would have a serious impact on trade and tourism across the border?