(From the opinion editors: The original headline on this editorial referred to tear gas being used on migrants last week at the Mexico-U.S. border as a "new low." In fact, as several readers have pointed out in letters and the Editorial Board should have reflected in the editorial, the U.S. has used tear gas in border enforcement under previous presidents, including Barack Obama. For more background, see a related Nov. 28 posting from PolitiFact at

Unbelievably, the Thanksgiving holiday weekend was marked by the United States firing tear gas at migrants — including women and young children — attempting to cross the border to claim asylum.

An instantly iconic photo captured the chaos of the scene: 39-year-old Maria Meza, wearing a Disney "Frozen" T-shirt, gripping the arms of her two young daughters — one in diapers — as they raced to escape the clouds of tear gas just behind them.

President Donald Trump, who previously opined that U.S. troops elsewhere along the border should shoot at those who threw rocks at them, defended the tear-gassing, saying some in the migrant crowd flung rocks at Border Patrol agents. It is hard to believe the agents had no other recourse than to indiscriminately fire tear-gas cartridges into the sovereign land of Mexico. Mexican officials rightly have called for an "exhaustive investigation." More must be known about this incident, which clearly crossed several lines in the severity of the U.S. response.

While not lethal, tear gas is a harmful substance that can cause severe eye pain, chemical skin burns, respiratory distress and pulmonary damage. Those effects are magnified in children, who also can suffer trauma from being gassed. Though used in this and other countries for riot control, the use of tear gas in war is prohibited by international treaties.

As we've written repeatedly, the U.S. has the right and obligation to control its borders. However, there also is little question that Trump's constant demonization of immigrants in general, his use of the "caravan" as a political prop during the midterm elections and his overly aggressive rhetoric and harsh policies have needlessly escalated the tensions that now exist at the border.

Avenues for refugees, asylum-seekers and others who seek paths to legal entry have been constricted needlessly under this president. Mexico has sought — and still seeks — cooperation with this country on comprehensive immigration reform that could head off some of these issues but has yet to find a receptive audience in this administration.

Trump and his functionaries have decried parents who would put their children in harm's way by bringing them to the border. Have they considered the level of fear it would take to force a mother to walk with her children from Honduras to the U.S. port of entry at San Ysidro, Calif.?

Border Patrol agents late last week confirmed that one 26-year-old Guatemalan mother of two attempted to scale a border fence there, fell and was hurt when she was impaled by rebar. Her children, ages 3 and 5, were taken into Border Patrol custody. These are among the people Trump has vilified as "criminals" and "rough people." Other asylum-seekers have said they have no choice but to try again because they fear gang violence and death threats in their home countries.

This is a humanitarian crisis, and the U.S. must find a humane way of dealing with it. Trump's threats to cut off aid to already-impoverished countries and to close off the southern border — with all the economic impacts that would carry for both nations — is a cruel and shortsighted path that will solve little.