During his latest presidential campaign, President Trump bragged about compelling Mexico to deploy 28,000 troops to its borders during his first administration to avoid tariffs.

This week, Mr. Trump and Mexico brokered another deal to send an additional 10,000 Mexican National Guard members to the border to stop the flow of migrants and drugs — a compromise to once again stave off U.S. tariffs. Mr. Trump has championed the agreement as a victory for the United States.

But analysts and former diplomats who brokered the first troop deployment in 2019 are doubtful that additional soldiers will have much effect thwarting the movement of migrants or drugs, particularly fentanyl.

Instead, they say, the deployment agreed to by President Claudia Sheinbaum of Mexico may be catering to Mr. Trump’s affinity for deal-making rather than being part of a well-thought-out military campaign.

“It’s a lot of shock and awe, but very little policy,” said Arturo Sarukhán, Mexico’s ambassador to Washington during President Felipe Calderón’s term from 2006 to 2012, an administration that aggressively pursued cartels inside Mexico, igniting extraordinary levels of violence nationwide.

The Mexican government appears to be echoing Mr. Trump’s fondness for a high-profile media blitz with its own.