When on 1st May 1923 the US government of president Warren Harding (1921-23) sent a long letter to Mexican government which included, amongst other issues, Mexican sub-soil rights to the US, president Alvaro Obregon (1920-24) could do anything but to accept such conditions.

There were three major issues between Mexico and the US.

1. The way in which the relatively newly introduced Article 27 in the 1917 Constitution (it deals with assets of foreigners in Mexico) was going to be applied which affected the agrarian reform and the US petroleum holdings in Mexico.

2. The damage caused to US assets in Mexican territory by the years of violence with the outbreak of the Mexican Revolution on 20/Nov/1910.

3. The foreign debt payment to be resumed. It had been stopped since 1917.

The Harding administration policy towards Mexico was emphatic as to the rights acquired by the US citizens residing in Mexico before the proclamation of the Mexican 1917 Constitution. The US will not recognise Mexico's government unless these rights were not guaranteed. What most offended the dignity of Mexico was that US wanted this to be as a 'Treaty of Friendship and Commerce'. President Alvaro Obregon and his cabinet rejected such condition as it would have been as to accept an unofficial protectorate status similar to that of Cuba at the end of the Spanish-US-Cuba War.

In the end, it was revealed that it was entitled as "Controversy sustained between the governments of Mexico and the United States on the occasion of the resumption of diplomatic relations". This was looked by the Mexican as a way of the US softening its approach towards Mexico. Nonetheless, on 13th August 1923 the two governments sat inside a building in the street of Bucareli in Mexico City and signed the Bucareli Treaty.

The treaty contains conditions which were mostly favourable to the US. 

It was also agreed that most of this document was not going to be fully disclosed to the public until 75 years later. But neoliberal president of Mexico, Ernesto Zedillo (1994-2000) in 1998 agreed to prorogue this term for a period of 25 more years till August 2023.

Notwithstanding the formality under which this treaty was signed, it was not easy for the US to fully implement it. The Mexican side, in general, never accepted it. In fact, President Plutarco Elias Calles (1924-28) who succeeded Obregon, pretended to comply with it but he later rejected it.

Current Mexican president, Andres Manuel Lopez Obrador, characterised for its firm policy against all forms of corruption, as well as self-determination and sovereign foreign policy, will most likely disclose the full document in August this year.