President Trump’s pardon of four Blackwater mercenaries, tried and convicted of mass murder in Baghdad during the Iraq War, is a clear signal that American soldiers and the paramilitary thugs who assist them can kill with impunity in wars of aggression launched by US imperialism. It sends a message about domestic as well as foreign policy. Trump is seeking to develop fascist forces, including sections of the police and military, who will be prepared to carry out similar massacres against American workers and youth.

Trump has been threatening to pardon the Nisour Square killers for several years, in the course of which he has pardoned several other convicted war criminals from Iraq and Afghanistan. The Blackwater guards have high-level support, both among Fox News pundits who are followed by Trump and within his own cabinet. His billionaire Secretary of Education Betsy DeVos is the sister of Erik Prince, Blackwater’s founder.

The circumstances of the 2007 Nisour Square massacre are not in doubt, following exhaustive investigations by the US military, the FBI and the Iraqi authorities. A squad of Blackwater mercenaries, deployed as guards for US State Department officials, left its base in the Green Zone, the US government’s compound in central Baghdad, on the morning of September 16, 2007, equipped with heavy weapons. At the first city square they entered, the mercenaries halted traffic and then opened fire indiscriminately with automatic weapons and grenade launchers on cars, taxis and buses carrying hundreds of ordinary Iraqis going about their daily business. No Iraqis fired shots, displayed weapons, or in any way threatened the Blackwater agents.

When the bloodbath was over, at least 14 Iraqis lay dead and 17 were wounded. None of the Americans suffered so much as a scratch. The death list demonstrates the essentially random character of the victims, 10 men, two women and two boys, hit in the hail of gunfire and explosives. There is no reference to these names in the pardon declaration issued by the White House:

• Ahmad Haitham Ahmad al-Rubai, 20, a medical student
• Mahassin Mohssen Kadhum Al-Khazali, 46, Ahmad’s mother and a dermatologist
• Ghaniyah Hassan Ali, 55, mother of eight, who died on a bus shielding her daughter Afrah from the bullets
• Ali Mohammed Hafedh Abdul Razzaq, 9, killed in the car his father was driving
• Mohamed Abbas Mahmoud, 47, a delivery truck driver
• Qasim Mohamed Abbas Mahmoud, 12, the truck driver’s son
• Mushtaq Karim Abd Al-Razzaq, 18, an Iraqi soldier standing at a military checkpoint
• Osama Fadhil Abbas, 52, a car dealer
• Ali Khalil Abdul Hussein, 54, a blacksmith commuting to work on his motorcycle
• Ibrahim Abid Ayash, 77, a gardener and passenger on a bus
• Mahdi Sahib Nasir, 26, a taxi driver
• Hamoud Sa’eed Abttan, 33, an unemployed job seeker, father of seven
• Uday Ismail Ibrahiem, 27, Hamoud’s cousin, also unemployed and a father of three
• Sa’adi Ali Abbas Alkarkh, 52, a businessman

The Nisour Square massacre came at the high point of the bloodletting in Iraq, when President George W. Bush had ordered a “surge” in troop deployments and operations throughout Iraq to forestall an impending disintegration of the Iraqi puppet regime established by the 2003 US invasion. The death toll skyrocketed with the ongoing clashes with Iraqi insurgent forces. It was impossible for US officials to move outside the Green Zone without heavily armed escorts, mainly provided by Blackwater, which held a $1 billion contract for guard services in the war zones. Mainly drawn from ex-military men turned highly paid mercenaries, Blackwater was characterized by a colonialist disdain for the “natives” and a penchant for shooting first and never asking questions.

The 2014 trial in the United States included 30 eyewitnesses flown in from Iraq to give testimony, the largest number ever to come to America for such a purpose. Their accounts were graphic and heart-wrenching. “Anything that moved in Nisour Square was shot. Women, children, young people, they shot everyone,” said Hassan Jaber Salman, a lawyer who survived the attack with his son.

Blackwater claimed that the convoy had come under attack, that the witness accounts were fabricated, and the killings were justified. However, a congressional report found that in 80 percent of the cases where Blackwater guards used their weapons in Iraq between 2005 and 2007, they had fired first.

Despite repeated interventions on behalf of the Blackwater mercenaries by US politicians and court rulings that overturned several guilty verdicts, four were finally convicted. Nicholas Slatten was the first to open fire, killing Dr. Al-Khazali and her son Ahmad, who was driving her to a medical appointment in a white Kia. Slatten was sentenced to life imprisonment. Three others, Dustin Heard, Evan Liberty and Paul Slough, joined in the killing. They received prison sentences ranging from 11 to 15 years.

At the time that the Blackwater killers were first convicted and sentenced, the WSWS wrote:

The Blackwater mercenaries were among the most flagrant killers in Iraq but hardly unique. There are numerous reported incidents of mass murder conducted by US soldiers, special forces operatives and private contractors. Many more such incidents are unrecorded because no victims survived. But some of these were among the hundreds of atrocities made public by Private Chelsea (Bradley) Manning, who released logs of military reports to WikiLeaks, some made public under the title “Collateral Murder.”

More importantly, the politicians and generals who organized and led the US war in Iraq have gotten off scot-free. Under the principles laid down by the Nuremberg Tribunal after World War II, the leaders of the US government during the Iraq War—George W. Bush, Richard Cheney, Donald Rumsfeld, Condoleezza Rice, Colin Powell, George Tenet, Paul Wolfowitz—and top military commanders from Tommy Franks to David Petraeus are guilty of the crime of planning and executing a war of aggression. They are collectively responsible for all the deaths that ensued as a result of their actions.

Today, many more names would be added to that list, including all the leading personnel of the Obama administration: Obama, Biden (now the president-elect and future distributor of pardons), as well as those who supervised drone warfare and larger-scale acts of military aggression in Iraq, Syria, Libya, Yemen and other countries.

There were perfunctory statements of outrage from congressional Democrats over the Trump pardons. “If you murder civilians while at war, you get a pardon,” said Representative Adam Schiff, chair of the House Intelligence Committee.

But Trump’s suppression of the Nisour Square convictions is only the crudest expression of a policy embraced by Democratic administrations as well as Republican. No one can forget that it was Obama who blocked all prosecutions of CIA officers for running secret torture chambers around the world, claiming that he wanted to “look forward, not backward.” What he looked “forward” to was using the CIA to carry out drone-missile assassinations all over the world, with American citizens among the victims.

President-elect Biden, who was Obama’s vice president, has already indicated that he will pursue the same policy, opposing prosecutions of Trump administration officials for such crimes as separating thousands of immigrant children from their parents, brutalizing and even killing migrants at the border, and carrying out flagrant violations of international law like the drone-missile killing of Iranian General Qassem Soleimani.

And while paying lip service to having learned the lessons of the bloodbaths in Iraq and Afghanistan, Biden has filled the national security positions in his cabinet and on his White House staff with advocates of and participants in these wars. He selected as his nominee to head the Pentagon, retired General Lloyd Austin, who was deputy to David Petraeus in 2008, during one of the bloodiest stretches of the war, and then held the top military command in Baghdad in 2010-2011, overseeing the final stages of the US withdrawal. Austin later headed the US Central Command as US troops poured back into Iraq to combat ISIS forces that were overrunning the Iraqi military.

The principal charge raised by the Democratic Party against Trump over the past four years was that he was insufficiently aggressive in prosecuting military operations in Syria and carrying forward the US military-intelligence onslaught against Russia initiated by the Obama administration. The replacement of Trump by Biden next month will not mean any lessening in the belligerence of American imperialism, only new dangers.

The struggle against imperialist war and barbarism requires the political mobilization of the working class, against both parties of imperialism, the Democrats as much as the Republicans, on the basis of a socialist and antiwar program.