U.S Customs and Border Protection (CBP) over the weekend shut down traffic flowing into the country at a key point of entry on the southern border.
The move comes as agents work to secure the U.S.-Mexico border in anticipation of the so-called caravan, which reportedly includes thousands of Central American migrants seeking asylum in the United States.
Lanes of traffic into the U.S. from Mexico at the San Ysidro Port of Entry have been shut down as agents lay down barbed wire, concrete and rebar to reinforce the entry point, NBC San Diego reported.
The San Ysidro port is the busiest land border crossing in the U.S., according to the outlet.
Pentagon officials earlier this month deployed thousands of active-duty military personnel to the border at Trump's request. Defense Secretary James MattisJames Norman MattisTrump's 'Enemies List' — end of year edition The US can't go back to business as usual with Pakistan The Hill's Morning Report - Presented by Facebook - Senate nears surprise deal on short-term debt ceiling hike MORE has emphasized that the troops are there as "border support" to help law enforcement as the migrants makes their way towards the country.
Trump on Saturday defended the decision to deploy around 5,800 troops to the border, saying, "They build great fencing, they built a very powerful fence."
“The fence is fully manned, nobody gets through," Trump added.
According to some estimates, the troop deployment could cost a total of $200 million, according to NBC San Diego.
More than 100 House Democrats earlier this month signed a letter to Mattis asking him to answer a number of questions on the mission, including its cost and duration.
Nearly 3,000 migrants arrived in Tijuana, Mexico, over the weekend. U.S. border inspectors are reportedly processing about 100 asylum claims a day at the border city's main crossing to San Diego, The Guardian reported.