The buses dropped them off in the town of Navojoa, in the northern state of Sonora, then returned to pick up a second group of 2,000 migrants who had stayed behind.
Now they have managed to outrun the caravan and have practically reached the United States border.
When asked about the cost of deploying troops to the border, Mattis said he will update the press as it becomes known.
Emma Stone Reveals That She Chose Her Name Because Of Baby Spice
We all know that the actress can sing, putting her pipes on display in 2016's "La La Land" opposite Ryan Gosling. She said at the time: "I wanted to dress like the Spice Girls [when I was a kid]".
Large groups of migrants have been gathering on the beach at the border fence that separates Mexico from California, shouting "We're not criminals!" in a pointed message to Trump.
Some migrants in a caravan of Central Americans have made long leaps forward in their journey to the US border, with a first sizable group arriving in the border city of Tijuana, while others on Wednesday were left stranded far behind. President Donald Trump has said the caravan of migrants amounts to an "invasion".
"We are expecting more of these little groups, but we don't know right now exactly what we are going to do with the big caravan", he said.
Over the past few weeks, the active-dutyservicemen deployed under Operation Faithful Patriot have mainly been erecting barbed-wire fences along the border in Texas, California and Arizona, as well as building shelter accommodation for customs and border protection staff.
Mattis gave no details in a brief comment to reporters Tuesday.
Death Toll Hits 25 From Wildfires At Both Ends Of California
Trump said "billions of dollars are given each year, with so many lives lost, all because of gross mismanagement of the forests". Rice also said Trump's assertion that California's forest management policies are to blame "is dangerously wrong".
Like most of those in the third caravan, migrant Javier Pineda is from El Salvador, and hopes to reach the United States.
Migrants were given an opportunity by the Mexican government to obtain asylum there, including work permits, healthcare, and other aid, but they rejected the offer when it was made clear they would have to settle in southern Mexico.
U.S. Department of Defence personnel install barriers requested by Custom and Border Protection at the San Ysidro port of entry, San Diego, U.S., under the Operation Secure Line anticipating the arrival of Central American migrants heading towards the border, as seen from the Mexican side of the border in Tijuana, Mexico, on November 13, 2018.
Beginning at 8 a.m. Tuesday, the agency will shut down three northbound lanes at the San Ysidro Port of Entry and one lane at the Otay Mesa Port of Entry.
Most of the roughly 5,000 migrants, most of whom are from Honduras, plan to turn themselves in at the San Ysidro Port of Entry and ask the USA government for asylum.
Michelle Obama 'stopped even trying to smile' at Trump inauguration
She writes that she felt she had "failed" after a pregnancy ended in a miscarriage. "Thank you, Oprah! " Obama tweeted Monday. Billed as "an intimate conversation with Michelle Obama ", it will take place before an audience of about 14,000.