Veterans of Foreign Wars, a prominent organization advocating for US military veterans, has called for Donald Trump to apologize for remarks downplaying brain injuries recently suffered by nearly three dozen American service members in Iraq.

The group was joined by several other US veterans’ organizations, criticizing Trump’s remarks and saying they showed a lack of understanding of injuries and what US troops face in overseas conflicts.

The VFW’s statement stems from Trump’s remarks on injuries resulting from a 8 January Iranian missile strike on a US base in Iraq. Thirty-four US soldiers suffered from concussion or traumatic brain injury (TBI) after the strike, which was a reprisal for the US drone strike assassination of the Iranian general Qassem Suleimani. Donald Trump had previously said that the US “suffered no casualties” from the attack.

“Veterans of Foreign Wars cannot stand idle on this matter,” William “Doc” Schmitz, VFW’s National Commander, said in a statement. “TBI is a serious injury and one that cannot be taken lightly. TBI is known to cause depression, memory loss, severe headaches, dizziness and fatigue – all injuries that come with both short- and long-term effects.”

“The VFW expects an apology from the president to our service men and women for his misguided remarks. And, we ask that he and the White House join with us in our efforts to educate Americans of the dangers TBI has on these heroes as they protect our great nation in these trying times. Our warriors require our full support more than ever in this challenging environment,” Schmitz said.

The statement also also come amid ongoing tension between Trump and military leadership. Multiple reports claim that former commanders – and active duty senior officers – complain that Trump has undermined chain-of-command.

Richard Spencer, who was fired as secretary of the navy fired after butting heads with Trump over war crimes cases, for example, said in a Washington Post op-ed “that the president has very little understanding of what it means to be in the military, to fight ethically or to be governed by a uniform set of rules and practices”.

Trump also became embroiled in controversy over an October 2017 condolence call to the widow of Sgt La David Johnson; she claimed the president said her husband “‘knew what he signed up for’” and didn’t remember his name.

It is now Trump’s statements after the Iranian attack which have caused upset.

“So far, so good”, Trump said after the strike. “I’m pleased to inform you the American people should be extremely grateful and happy,” Trump said. “No Americans were harmed in last night’s attack by the Iranian regime.

After the Pentagon announced on 16 January that troops were being treated for concussion symptoms, Trump claimed the discrepancy was because he heard about the injuries “numerous days later”. Trump also downplayed the severity, saying, “I heard that they had headaches. And a couple of other things. But I would say, and I can report, it is not very serious.”

“I don’t consider them very serious injuries relative to other injuries I have seen. I’ve seen people with no legs and no arms,” he said.

Eight of the injured service members were considered in serious enough condition to be moved to the US.

“The President’s comments show a lack of understanding of concussions, TBI, and what our service members face in conflicts overseas,” said Jeremy Butler, Iraq and Afghanistan Veterans of America CEO, in an email to The Guardian. “This is why IAVA works so tirelessly to educate the American public, including the president, about the issues facing today’s service members and veterans.”

Joe Chenelly, national executive director of AMVETS, told The Guardian in an email: “We are working with the White House on this to ensure the president is aware of the seriousness of even the slightest concussions, which are in fact brain injuries.”

“Further, this is an excellent opportunity to raise awareness of the realness and severe impact all invisible wounds can have on humans,” Chenelly continued. “We also are pleased the Administration has shown constraint in not escalating the military conflict with Iran.” The White House did not immediately respond to a request for comment.