(CNN)For those standing on its northern side, near San Diego, a fence that divides the United States and Mexico is little more than a physical barrier made of welded metal and steel.
Deported vets helped paint this upside-down US flag on the border. Will they have to remove it?
But just a few yards to the south, near Tijuana, the fence there evokes emotion. For years, artists and community groups have transformed portions of the wall into vibrant visual statements about hot-button issues involving the two countries, such as immigration, human rights and foreign policy.
One mural depicts colorful butterflies swirling around an outstretched hand in a gesture of friendship and unity. In another, the top of the fence gradually disappears as it matches the color of the sky. Some have painted crosses mourning the migrants who have died while traveling through remote stretches of the US Southwest.
And then there's one painting that seems to stand out from the rest. It's an upside-down US flag, with similar crosses. In 2013, a group of deported US military veterans helped paint what they call a symbol of distress for their situation.
Now, they say they are being told by the US government -- which owns the fence and the grounds near it -- to remove or alter the painted flag. The US Border Patrol said it has received complaints about some of the border art and is trying to decide whether they are graffiti or "intentional" murals. It says the paintings were applied without permission.
While questions arise over whether there is room for compromise, the man who first conceived of the design says he is refusing to change it. He says the federal government is trying to squelch free speech -- after five years of no formal objection.
"What we want to do is raise awareness around the issue of deported veterans. It's not about us trying to take on our own government or us trying to create imagery that's hostile toward the United States of America," said Amos Gregory, a San Francisco-based visual artist and a disabled US Navy veteran. He is a US citizen, and while he does not live in Tijuana, he periodically goes there to assist the veterans on other paintings.
The colorful paintings are primarily in an area along the border known as Friendship Circle. Here, San Diego is separated from Tijuana by a pair of parallel running fences that are about 12-15 feet high and 40-50 feet apart.
Friendship Circle, which sits in the space between the structures, is supervised and periodically opened by the US Border Patrol. Family members from both sides of the border meet to have what have been described as "pinky kisses" through a metal mesh and talk.
The fence closest to and facing the Mexican side includes the artwork considered murals by their creators.
Gregory worked with a group of about 20 deported veterans to install the inverted flag painting. Since then, the group has grown to about 60 as more recent deportees began adopting and supporting the project. They periodically touch up the paint when it begins to fade because of salt and moisture from the nearby Pacific Ocean.
Through his work in San Francisco, where he founded the Veterans Mural Project, or Veterans Alley, in the Tenderloin District, the artist discovered the therapeutic effects of painting murals for himself and fellow veterans.
When he realized that another population of veterans -- those deported to other countries -- could benefit from what he says are the healing powers of art, but could not travel to the US to participate in the project, he brought the project to them in 2013.
They realized only one image made sense.
"We want to send an SOS to the American people and to other US military