In yet another devastating blow to refugees fleeing violence, chaos and deprivation in Central America, on September 11, the US Supreme Court allowed the Trump administration to implement a near-total ban on asylum seekers at the southern border while litigation seeking to block the rule proceeds.

Issued in July, the rule functionally bars asylum for migrants – including unaccompanied children – who arrive at the southern border after travelling through a third country without being denied asylum there first. Its implementation will have catastrophic consequences for refugees and worsen the escalating humanitarian crisis that US President Donald Trump’s racist policies have already unleashed.

Aimed primarily at refugees from the Northern Triangle countries of El Salvador, Honduras and Guatemala, the ban also applies to migrants from South America, Africa and elsewhere. The move is the latest salvo in Trump‘s xenophobic efforts to close the US to migrants he deems undesirable, including his Muslim ban, the “metering” process controlling who can access the southern border to request asylum, and his “Remain in Mexico” programme, which has stranded more than 40,000 migrants in harrowing conditions as they await processing of their asylum requests.

He has also worked to systematically eviscerate asylum standards, both substantively and procedurally, while attempting to deter asylum seekers through calamitous family separations and horrific conditions of detention, all amid reports the administration is contemplating dramatic new reductions in refugee admissions. Immigration policies were deeply flawed before Trump, but they have grown immeasurably crueller under his watch.

The right to petition for asylum is enshrined in domestic and international law. The 1951 Refugee Convention and 1967 protocol evince a global understanding of collective responsibility to shelter those seeking refuge from persecution, and is incorporated into US law. The Immigration and Nationality Act holds that a noncitizen who is physically present or arrives in the United States may apply for asylum, with two exceptions: when she is “firmly resettled” in another country first, or is covered by a safe third country agreement.

Neither transiting through a country, nor being forced to wait there constitutes firm settlement.The latter exception requires a formal agreement between the US and the third country that ensures a host of safeguards to protect migrants from persecution and full and fair procedures to adjudicate their asylum claims.

Given the pervasive criminal networks, inadequate infrastructure and lack of political will to protect migrants’ rights, and growing hostility towards them, the suggestion that Mexico or its immediate southern neighbours can satisfy this standard is tragically absurd. Already grim conditions at the border are deteriorating as refugees await their fate.

To shore up his actions, Trump has attempted to strong-arm Mexico and Guatemala into signing safe third country agreements. Despite widespread opposition in his country, outgoing Guatemalan President Jimmy Morales agreed to sign the deal, though the fate of the accord remains unclear.

Mexico, which has thus far resisted a formal agreement, is cracking down on refugees at Trump’s behest. His administration is reportedly seeking similar agreements with Honduras and El Salvador, despite the bitter irony that it is precisely the mayhem and misery in these countries from which the refugees are fleeing.

In addition to running afoul of the law, the ban is unconscionable, given the US’s long and sordid role supporting rights-abusing regimes in Central America. Washington continues to provide security aid for governments that engage in state-sponsored repression and embrace militarised counter-narcotics and anti-gang policies that stoke violence, and ignores systemic corruption. Trump is exhorting the countries to embrace a militarised approach to immigration enforcement as well.

Economically, the US has promoted its neoliberal agenda through trade policies and international financial institutions that enhance the climate for US investors while further immiserating the poor. And as he railed against refugees, Trump punitively slashed aid to the Northern Triangle earlier this year in a move that even puzzled many of his supporters. The violence and poverty afflicting Central America do not occur in a vacuum.

Though misguided US policies are long-standing, Trump’s patent indifference to corruption and human rights removes the pretence of concern about the plight of beleaguered Central Americans.

His administration turned a blind eye when embattled Morales threw out the well-respected UN-backed anti-corruption commission CICIG after the body put him and his family in its crosshairs for graft, and is standing by Honduran President Juan Orlando Hernandez despite the tainted 2017 election and mounting evidence of corruption, including links to drug-traffickers. His brother Tony Hernandez is currently awaiting trial in the US on drug and weapons charges.

The US has contributed to the humanitarian crisis in other ways as well. It is the primary consumer of drugs flowing through the region, and its lax gun control laws make arms trafficking lucrative and cartels more deadly.

Less directly but no less consequentially, climate change is increasingly driving migration from Guatemala, Honduras and El Salvador, where drought, hurricanes, and mudslides are rendering areas uninhabitable, exacerbating food insecurity and poverty, and threatening employment for the roughly 30 percent of people who work in the agricultural sector.

These countries have been responsible for a vanishingly small amount of the carbon emissions that cause climate change, while the US’s historical contributions have been immense. Though the World Bank warns that extreme weather could drive between 1.4 and 2.9 million people to flee their homes in Mexico and Central America over the next three decades, Trump calls climate change a hoax and guts efforts to ease the coming catastrophe. Displacement will only grow worse.

The US has built its prosperity on a global economy that has bled Northern Triangle countries dry, and long propped up the corrupt and brutal governments that serve its own geopolitical interests, irrespective of the human costs. Washington bears a deep moral responsibility to mitigate, not worsen, the staggering humanitarian crisis that its past and present policies have helped to create.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.