Mexico has announced the deployment of up to 15,000 soldiers and police to its northern border with the United States to help stem migrant crossings, said Secretary of Defense Luis Sandoval.

"In the northern part of the country, we have deployed a total of almost 15,000 troops composed of National Guard elements and military units," according to Sandoval.

In a dig at the Trump administration, Sandoval later said "Migration is not a crime, it is an administrative responsibility.”

Sandoval also made the surprising announcement 2,000 National Guard troops have already been deployed to Mexico's southern border with Belize and Guatemala. They will reinforce the 4,500 troops already there.

The deployments hold-up Mexico’s part of the deal with the Trump administration to help slow migration to the United States. Mexico, however, has also called on the United Nations, the United States and other countries to help with this intractable problem.

Mexican president Andres Manuel López Obrador in May said “formal, national operations” to police the borders will officially begin on June 30.

Mexican political pundits said Sandoval’s announcement 2,000 National Guard troops are already at the border is unbelievable since the first National Guard recruits will graduate from training camp only at the end of this month.

Unlike Sandoval, other Mexican officials have refused to say how many National Guard troops are part of Mexico’s border control campaign.

The fledgling Mexican National Guard was only organized at the start of the year specifically to fight organized crime and drug cartels and not to deal with migrants. It consists of members of the Federal Police and military police units of the army and navy.

It hasn’t received any training in border protection or migration enforcement. The National Guard is controlled by the civilian Ministry of Security and Citizen Protection.

It was organized “to deal with organized crime and security, not to interdict migrants, which are not a security threat for Mexico,” according to Adam Isacson, director for defense oversight at the Washington Office on Latin America, a research and advocacy group.

To the National Guard, however, will eventually fall the responsibility for policing Mexico’s border with the U.S. and with Belize and Guatemala. Most migrants headed for the U.S. come from these two countries and from Honduras.

The National Guard will be supported by the Mexican Army (Ejercitos Mexicano) and the Naval Infantry Corps (Cuerpo de Infantería de Marina), Mexico’s equivalent of the U.S. Marines. It will only graduate its first recruits later this month.