“It’s an act of aggression quite frankly, if you station the military at your perimeter what does that say about your relationship with the neighbouring country,” Andrea Guerrero, the executive director of rights group, Alliance San Diego, told Al Jazeera.
“The military’s presence on the border will escalate the tension between the two countries and our fear both here and in Mexico that will lead to tragedy,” she said.
Trump made the announcement at a White House luncheon with Baltic delegates on Tuesday, saying that “until we can have a wall and proper security, we’re going to be guarding our border with our military”.
“I spoke with [Defence Secretary James] Mattis, we’re going to do some things militarily,” he said.
“We cannot have people flowing into our country illegally, disappearing, and by the way never showing up for court.”
The proposal has brought about criticism from those on both sides of the political aisle, as well as from rights groups who pointed that a border wall and fence already exists on much of the US-Mexico border.
“He says we need these troops because we do not have a wall – that is not true, we do. We have 700 miles of a wall,” Guerrero said.
“We are not at war with Mexico and there’s no military threat facing us. There’s no justification for the military,” she added.
Tara Tabassi, an organiser for the rights group War Resisters League, which seeks to end war and its causes, said that its wrong to assert that the US-Mexico border is not already militarised.
“Let it not be mistaken, the US-Mexico border is already militarised, and the addition of soldiers and a wall will only serve to further harass, criminalise, and endanger refugees and migrants fleeing economic and political violence created and sustained by US policies and intervention,” Tabassi told Al Jazeera.
“Trump’s call only enforces the long-standing practice of using US military personnel as a tool of white supremacy to protect profits over people,” she added.
Both George W Bush and Barack Obama deployed the National Guard to the US-Mexico border during their presidencies.
“The last time we had the military deployed at the border in the form of the national guard that happened in Texas, that resulted in a border resident, a young by the name of Esequiel Hernandez being killed,” Guerrero said.
“The military personnel were not equipped or trained to handle what they believed was an immigration incident, although the gentleman was a US-citizen,” she added.
“Their presence resulted in racial profiling.”
According to rights group, Southern Border, at least 50 people have died as a result of an encounter with US border agents since 2010.
Trump’s comments on Tuesday came off the back of a series of tweets criticising Mexico for its immigration policies and calling on Congress to pass strict immigration laws, as well as fund his border wall.
According to US media, many defence officials were unaware of Trump’s plan to militarise the border and were not sure exactly what he meant by the comments.
Trump also repeated his threat to pull the US out of the North American Free Trade Agreement (NAFTA) with Mexico and Canada.