Telling reporters that details of the deal were a “secret”, the President waved a piece of paper with plans written on it.
And some of those plans could be read relatively clearly as photographers took pictures of it.
The paper revealed that Mexico is to be considered a “safe third country” - meaning asylum applications would be processed there instead of the United States.
It also stated that Mexico had committed to doing everything it could immediately to become a safe third country.
Other details included a reference to “45 days” - the amount of time for Mexico to show it can reduce the flow of migrants across the border with the US before other Latin American countries got involved in processing asylum claims.
Read more from Yahoo News UK:
Mexican Foreign Minister Marcelo Ebrard said yesterday that the country is now deploying some 6,000 National Guard personnel to the border with Guatemala.
He added: "You go to the south and the first thing you ask yourself is, 'Right, where's the border?' There's nothing.
”The idea is to make the south like the north as far as possible.”
Mexico has so far rejected plans to be designated a safe third country if this plan fails.
Mr Ebrard said: "We told them - I think it was the most important achievement of the negotiations - 'let's set a time period to see if what Mexico is proposing will work, and if not, we'll sit down and see what additional measures [are needed]’.
"They wanted something else totally different to be signed. But that is what there is here. There is no other thing.”
Mr Ebrard added that Mexico had also dismissed US demands to see the country commit to "zero migrants" crossing its territory.