Things just got more "complicated" in US-Mexican relations, when on Thursday morning the feud between the US and Mexico deepened after president Pena Nieto said he canceled a planned summit with Donald Trump over the US president's insistence that Mexico pay for his proposed border wall between the two countries.

"This morning we have informed the White House that I will not go to the meeting scheduled for next Tuesday with "POTUS," Enrique Peña Nieto tweeted in Spanish.

The fresh deterioration in diplomatic relations between the US and Mexico came after the US president tweeted earlier on Thursday that if "Mexico is unwilling to pay for the badly needed wall, then it would be better to cancel the upcoming meeting".

"The US has a 60 billion dollar trade deficit with Mexico. It has been a one-sided deal from the beginning of Nafta with massive numbers of jobs and companies lost," Trump added on Twitter, underlining his determination to renegotiate the North American Free Trade Agreement.

Peña Nieto had initially resisted heavy domestic pressure to cancel the meeting with Mr. Trump. Mexican foreign minister Luis Videgaray told local TV station Televisa on Wednesday "for now, the meeting is still on". Instead, Mr. Videgaray had sought to take the sting out of a potentially highly damaging diplomatic dispute, highlighting some "very encouraging" signs from Mr. Trump and his team and an "outstanding willingness" to work together, despite what he said had been "a day of contrasts".

Nieto decided to pull a Trump, and make the public statement from his own Twitter account:

After canceling his trip, Pena Nieto added that his still wants to work with the US, and reach accords.

Vicente Fox, the former Mexican president, stoked the flames in cruder terms in a series of tweets. "Donald, don't be self-indulgent. Mexico has spoken, we will never ever pay for the #F**kingWall," he tweeted on Thursday morning.

And just like that NAFTA may be over. And the peso is plunging…

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