Does My Mom Have To Go To Court In A Different Country For A Divorce That Happened 4 Years Ago?

This is fucking nuts, and I'm not looking for any in-depth legal help, I just need to know if this is even... I don't know, a legitimate threat??

So my parents moved to the US in 2009, and were naturalized in 2015. They divorced in 2020, a process that was finalized and resolved in 2021. For some context, my dad is utterly batshit insane. He was very abusive to my mom and still wants to control her and get revenge against her. My brother and I were both (barely) minors when the divorce happened and we still live with our mom full time.

One of my dad's talking points during the divorce was how my parents are still technically married in our home country. My brother and I always responded that it didn't matter. My dad is a real piece of work and wants to get revenge on my mom, so he dregs up bullshit reasons to drag her to court or get money out of her.

Today, my mom got a letter from the embassy of our home country that my mom is summoned to court in our home country for a divorce hearing on December 21. Our home country is Iraq, if that's important for extradition reasons or anything. I don't know if my state is important because this feels more like a federal problem, but I live in Missouri.

My mom's theory is that he wants to divorce us in our home country because he owns assets there, and by law, if he dies we get a portion of it. My dad is extremely greedy and won't give anyone a penny if he won't benefit from it, so this makes sense to me, but I know nothing about international divorces and don't know if that's even plausible.

I just... Is this actually allowed? Does the marriage even count if they haven't been citizens of Iraq in almost a decade and divorced in the country they are now citizens of? Will anything happen to my mom if she doesn't show up (because she can't)? Tickets home are at least $2,000, and no one in this family makes enough for that.