Walmart, the country’s largest retailer, is halting donations from its political action committee to the campaigns of congressional Republicans who opposed certifying President-elect Joseph Biden’s election, joining defense giant Northrop Grumman and other major corporations taking a stand against violent riots many believe were sparked by President Trump in an effort to overturn the November election.

“In light of last week’s attack on the U.S. Capitol, Walmart’s political action committee is indefinitely suspending contributions to those members of Congress who voted against the lawful certification of state electoral college votes," the company said in a statement Tuesday.

On Monday evening Northrop Grumman became the first defense manufacturer to halt all donations from its political action committee, joining a growing corporate backlash against the Capitol violence Wednesday. Several other large government contractors, including Raytheon Technologies and BAE Systems, later followed suit.

In the days since Trump supporters temporarily halted the certification of Biden’s election win in attacks that left a police officer and four others dead, many well-known brands have rebuked the president and members of Congress seen as enabling him.

AT&T, Marriott, the Blue Cross Blue Shield Association and American Express were among many that said they would withhold donations from their political action committees to lawmakers who voted against certifying Biden’s win. Others — including Google, Microsoft and BlackRock — said they were halting all political donations from their PACs.

Walmart’s PAC last year donated $1.2 million, split evenly between Democrats and Republicans, though its contributions in previous election cycles have typically skewed Republican. The Bentonville, Ark.-based retailer said in a statement that it assesses and adjusts its political giving strategy at the end of each election cycle, and will continue its review in coming months.

Last year, Northrop Grumman’s PAC also contributed roughly equally to Democrats and Republicans.

“We are pausing political action committee giving and evaluating the way forward,” said Northrop Grumman Vice President of Communications Tim Paynter. Northrop Grumman did not release a statement explaining its decision.

Northrop Grumman’s move to halt donations is significant in an industry generally reluctant to criticize the commander in chief.

Trade associations representing the defense industry issued statements publicly condemning the violence, but did not directly criticize Trump or single out congressional Republicans. Aerospace Industry Association President Eric Fanning condemned the riots along with “those who incite such violence" without naming Trump directly. National Defense Industrial Association President Hawk Carlisle called the riot “despicable” for causing a “breakdown of the rule of law” and “the desecration of the Capitol building.”

Some of Northrop’s peers at the top of the U.S. defense industry ― Lockheed Martin, Boeing General Dynamics ― had not halted donations or issued statements as of Tuesday afternoon.

But three other large government contractors later confirmed Tuesday they would halt donations.

Raytheon Technologies, a massive Massachusetts-based defense-tech company that formed through a merger of Raytheon and United Technologies, halted all contributions to “reflect on the current environment and determine appropriate next steps,” said Raytheon spokesman Chris Johnson.

Leidos, a Reston-based company that specializes in government IT and other technology services, paused all political donations because “democracy thrives on passionate debate and different opinions but dies in anarchy and violence,” as Chief Executive Roger Krone put it in a statement Tuesday.

And BAE Systems Inc., the U.S. subsidiary of a British defense manufacturer, reacted to what spokeswoman Tammy Thorp referred to as “disturbing” events at the capitol.

“In response to the deeply disturbing violence at the U.S. Capitol on January 6th, our U.S. political action committee has suspended all donations while we assess the path forward,” Thorp said.

The defense industry, through sophisticated lobbying operations and a manufacturing supply chain spanning all 50 states, has long held significant sway in Congress. It is also a prolific contributor to political campaigns, including those of the 147 Republicans who voted to overturn the November election.

An analysis by the nonprofit Center for Responsive Politics found four defense firms among the top 20 contributors to the campaigns of Republicans who objected to Biden’s win. Northrop Grumman was 10th among them with $687,500 donated to lawmakers who objected to the election.

Political giving from Northrop Grumman’s employee-funded PAC reached $4.8 million last year according to the nonprofit — its highest point in at least 30 years. Contributions from the PAC in 2020 were roughly evenly split, slightly favoring Democrats. Between 2014 and 2020 Republicans received more from the company.

Northrop Grumman’s PAC has previously contributed to several of the lawmakers who led the effort or voted to overturn the election results. From 2015 to 2020 the PAC gave $5,000 to the campaign of Sen. Josh Hawley (R-Mo.), according to the Center for Responsive Politics. In the most recent election cycle, it gave $15,000 to the campaign of Rep. Devin Nunes (R-Calif.) and $10,000 to Rep. Mo Brooks (R-Ala.), among others who voted to overturn the election.

The defense industry has in many ways walked in lockstep with Trump since he took office. The industry has benefited significantly from increased military spending under Trump, as well as the president’s support for international arms sales. Lockheed Martin became a centerpiece of a White House-sponsored advertising campaign highlighting the administration’s job creation credentials.

When Trump blamed “both sides” for violence at a Charlottesville white supremacist rally in 2017, defense firms were among the few companies that supported the president’s business councils. Other corporations left the councils in protest, leading to their dissolution.

Northrop Grumman was not a part of the president’s business councils even before the Charlottesville rallies. But the company suffered its own fallout from the rally when ProPublica and the television program “Frontline” identified one of its systems engineers as a member of a white supremacist organization. Northrop Grumman fired the engineer after a video surfaced showing him punching a Black man at the Charlottesville riot.