Washington — Secretary of State Mike Pompeo on Monday hailed the agreement reached with the Mexican government last week, saying the "full-blown" expansion of a policy to return Central American asylum seekers to Mexico will make a "fundamental difference" in curbing large-scale migration.

As the U.S. prepares for the immediate expansion of the Migrant Protection Protocols (MPP) program — dubbed "Remain in Mexico" — Pompeo said U.S. authorities have increased their capacity of returning non-Mexican migrants who claim asylum at ports of entry along the southern border to Mexico.

"We were able to do this to the tune of a couple 100 people per day," Pompeo said during a press briefing at the State Department. "We now have the capacity to do this full throttle and engage this in a way that will make a fundamental difference in the calculus for those deciding to transit Mexico to try to get into the United States."

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"This full-blown effort under the Migration Protocols is a big deal," he added, referring to the "Remain in Mexico" policy.

Secretary of State Mike Pompeo speaks to members of the media at the US State Department, Monday, June 10, 2019. Pablo Martinez Monsivais / AP

Since "Remain in Mexico" was first implemented in December 2018, U.S. authorities have returned more than 10,000 migrants to Mexico, according to the Mexican government. The policy — which is being challenged in court — is currently in place at the ports of entry in San Diego, Calexico and El Paso.

On Wednesday, a Department of Homeland Security (DHS) official told CBS News that Friday's deal represented the "first time" the Mexican government had agreed to the "full and immediate expansion" of "Remain in Mexico."

"The scale of Mexico's new commitment is dramatic," the official added.

For days, President Trump threatened to authorize tariffs on all Mexican products traveling across the southern border unless Mexico's government undertook more efforts to reduce migration from Central America, including tightening its border with Guatemala.

On Friday, however, Mexican and U.S. diplomats drafted a joint resolution vowing to curb the unprecedented surge of families and unaccompanied children from El Salvador, Honduras and Guatemala heading to the U.S.-Mexico border. Last month, U.S. authorities apprehended more than 133,00 people near the southwestern border — a 13-year high.

Under the agreement, the Mexican government vowed to deploy National Guard units to the Guatemala-Mexico border, while the Trump administration indicated it would expand "Remain in Mexico" along the entire border.

Although Mr. Trump claimed on Twitter that Mexico also agreed to purchase "large quantities" of American agricultural goods as part of negotiations between both countries, the Mexican Ambassador to the U.S. Martha Bárcena Coqui refused on several instances to confirm on "Face the Nation" whether her government consented to such a deal.