Yesterday, U.S. Customs and Border Patrol agents fired tear gas at hundreds of people, including women and children, after some of them tried to force their way across the border between San Diego and Tijuana, Mexico.
Our chief correspondent Stuart Ramsay and his team have been on the front line of the migrants' struggle to make it across.
Mexico has no intention of deploying its troops to curb the influx of migrants arriving at the country's border with the United States, the Mexican Foreign Ministry said in a statement.
An estimated 8,200 migrants from the so-called caravans heading to the US from Central America are now in Mexico, authorities say.
"Children screamed and coughed".
On Sunday, Mexico promised to shore up security along the border, and the country's Interior Ministry said it would immediately deport those who tried to "violently" enter the USA from Tijuana.
Pedestrians prepare to enter the U.S. at the San Ysidro port of entry.
Trump has repeatedly suggested without evidence that the migrant caravans are full of hardened criminals, but they are mostly poor people with few belongings who are fleeing gang violence.
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U.S. Customs and Border Protection has defended its decision to use tear gas, claiming that some migrants with the group had thrown projectiles across the border, hitting several agents.
Needless to say, it's an intense scene. By Sunday afternoon, CBP reopened crossing lanes in both directions to pedestrians, CBP representative Jackie Wasiluk said.
"As I have continually stated, DHS will not tolerate this type of lawlessness and will not hesitate to shut down ports of entry for security and public safety reasons", she said, adding the United States would "seek to prosecute" offenders.
Trump has called on Mexico and countries farther to the south to take actions that would prevent such migrant caravans from ever reaching the US border.
Trump administration officials have characterized the vast majority of asylum claims as fraudulent or legally insufficient, and have taken steps to reduce the backlog of asylum claims that they say are often used by migrants to gain entry into the USA and disappear into the country as their claims are adjudicated.
But Mexico's incoming government, which assumes power December 1, denied that it is willing to let USA asylum-seekers stay there pending the outcome of their cases in US immigration courts, which could take years.
Hours earlier, The Washington Post had quoted her as saying that the incoming administration of Andres Manuel Lopez Obrador had agreed to allow migrants to stay in Mexico as a "short-term solution", a plan dubbed "Remain in Mexico".
Earlier in the morning, a group of Central Americans staged a peaceful march to appeal for the U.S.to speed up the asylum claims process, but their demonstration devolved as they neared the crossing with the USA and some saw an opportunity to breach the border.