When President Trump tweeted on Wednesday morning that he would ban transgender people from serving in the US military, Democrats, and even some Republican members of Congress, shared their opposition on Twitter.

Now a prominent retired Navy admiral, John Kirby, is speaking out against the ban. In a seven-tweet thread on Friday, Kirby said, “US military IS a microcosm of American society & should be representative of that society — ALL of it. Diversity is a strength.”

Kirby’s tweetstorm began just after noon on Friday, after deputy assistant to President Trump Sebastian Gorka tweeted support for his boss’s proposed ban. “We refuse to treat the American military as an ideological petri dish. Obama-era social engineering is over.”

Under @realDonaldTrump we refuse to treat the American military as an ideological petri dish.



Obama-era social engineering is over. https://t.co/2tkGIH9OPW — Sebastian Gorka DrG (@SebGorka) July 28, 2017

Kirby responded almost immediately, attacking Gorka, who has never served in the armed forces, and urging him to stay out of the military’s affairs.

1/Normally I ignore .@SebGorka. But this is offensive. I can't sit by as someone who never wore our uniform pretends he knows what it means. https://t.co/FsB9moWKws — John Kirby (@johnfkirby63) July 28, 2017

Kirby isn’t a politician or partisan operative. After serving with the Navy for 29 years, he retired in 2015 and worked as a State Department spokesperson from 2015 to 2017 under President Obama. His tweetstorm shows how appalled much of the military community is over Trump’s proposed ban — one that top military officials have stressed won’t take effect anytime soon.

In one of his first tweets, Kirby said he would usually ignore Gorka, but that the White House aide’s “offensive” tweet caught his attention.

“I can't sit by as someone who never wore our uniform pretends he knows what it means,” Kirby wrote.

Throughout the thread, Kirby emphasized that diversity in the US military is important and that anyone who meets the military’s high standards should have the opportunity to defend the country.

2/Fact: US military IS a microcosm of American society & should be representative of that society – ALL of it. Diversity is a strength. https://t.co/yCBuJBtlfO — John Kirby (@johnfkirby63) July 28, 2017

3/We're an all-volunteer force w/high standards. If you meet those standards -- in THIS country -- you should have opportunity to defend it. https://t.co/jpJLi8WRfl — John Kirby (@johnfkirby63) July 28, 2017

He also correctly pointed out that there have been no disruptions in military operations in the 13 months since Obama cleared the way for transgender troops to openly serve in the military.

4/Transgender troops serving openly for more than a year with no disruptions to unit cohesion, no morale probs, NO impact on readiness. https://t.co/VptMlRWBJG — John Kirby (@johnfkirby63) July 28, 2017

Kirby went on to say that transgender troops actually “make us stronger,” mentioning retired Navy SEAL Kristin Beck as an example.

Beck served for 20 years and received a Bronze Star, a Purple Heart, and 27 other medals. After Trump announced the ban, she had something to say to the president: “Let's meet face to face and you tell me I'm not worthy," Beck told Business Insider. “Transgender doesn't matter. Do your service.”

5/Quite to contrary, the skills these troops bring to the fight – just like that of former Navy SEAL Kristin Beck – make us stronger. https://t.co/W7FyK9gcrK — John Kirby (@johnfkirby63) July 28, 2017

6/Go ahead, tell her all about how to kill people and blow things up. I'd love to see how that conversation goes. https://t.co/kHeYSRPEu9 — John Kirby (@johnfkirby63) July 28, 2017

Kirby ended his thread by knocking Gorka again, along with anyone else in the Trump administration who hasn’t served in the military, for trying to decide policy without consulting any generals or military experts.