This is yet another reminder that the insurgency is arch-cope. It's been three months and there's been 0 (zero) partisan armies or guerilla on Russia-controlled territories. Afghanistan was a mountainous territory easily lending itself to places for insurgents to hide out, with a highly motivated and majority young population, with a massive TFR of around 7.5 at the time of the US and Soviet invasions and that's over 4 even now. The Ukrainian TFR by contrast is 1.2, below even Russia, with flat terrain and majority older population, with over six million people having migrated out already, predominantly the youngest and most able to work.
Yeah, the insurgency won't be as effective as Afghanistan, but it is at least accomplishing goals in Melitopol. The goal is to make holding territory more than it's worth. The biggest weakness the resistance has is Russia is aware of it, and is using the old deportation method to deal with it (send people not-completely-loyal to Siberia, move in completely loyal Russian citizens and give them free real estate).
An insurgency really needs sympathetic locals to help hide it. Russia is removing that. That's why even in the best case Ukraine will never be able to go past the pre-February borders -- LPR/DPR and Crimea were already cleansed. Most people there are loyal to Putin now. The rest either escaped west or are chopping wood in the taiga. Ukraine will be lucky to get back Kherson and Melitopol.
The Taliban banned marriage under age 15. Without getting into an autistic slapfight about definitions, social censure of sex with prepubescent children is far closer to a universal human behavior than drawing a bright line between "child" and "adult" at age 18.
The Taliban did not ban marriage under 15. That's just their requirement for wives recruited through official programs as a reward for their troops. If locals want to marry younger, they can (within the limits of Sharia, nobody under nine and depending on the local administrator they might demand menstruation first). They also banned forced marriage, though it's kind of hard for an 11-year-old girl to say no when everyone around her is pressuring her.
The USA, by comparison, gets a lot of immigrants, both legal and illegal. This keeps the overall age of the American population lower than China, Japan, South Korea, or Russia. Ensures X number of workers to support each retiree.
Thankfully most US immigrants come from Latin America, especially Mexico. They're largely culturally compatible and by the second generation they're usually totally integrated. The US just needs to do a better job keeping the criminal element out and definitely needs to do a better job to prevent ghettoization. The average 2nd generation Mexican-American is better integrated than the average 20th-generation African-American.
Europe is fucked because they keep taking in people from totally incompatible cultures. Not just Muslims, but Africans from those bizarro Christian countries that never moved beyond Spanish Inquisition-style shit. It's mostly not a Christian/Muslim issue, it's a secularism and social contract issue. Malaysians integrate fine.
no reform will un-immigrate dozens of millions of hostile foreigners.
you'd have to do large scale mass deportations to fix this situation, which is not possible in a liberal democracy.
Breaking up ghettos might be possible. The worst immigrants in Europe live in social housing. Spread out the social housing so the kids don't have a bubble as their only social interaction.
Lots of Spanish-speaking cultural Mexicans in Texas. They could try to go about forming their own state through normal means (eg State of Jefferson on west coast) with support from Mexico but beyond that, imagine if Texas sent in their state militia to force Spanish-speakers in the South to stop attempting to form their own state and then passed laws saying every official sign, document, and even unofficial media and then some must be in English. Effectively barring Spanish from the state.
Not a perfect comparison but close enough I hope.
The US doesn't have a national language, but there are federal policies that everything the government posts has to be in English. It is, however, not prevented from having a secondary language also presented. Similarly, there are dual-language public schools but they are absolutely required to teach English with the expectation that by Jr. High every class will be in English.
As for your statehood example, Spanish-speakers in Texas would not be able to form their own state without the consent of congress, and of Texas itself. That's been the rule since Kentucky split from Virginia and Maine split from Massachusetts. If they unilaterally declared a state, even after a referendum, you bet your ass the troops would come in just like they did with the State of Deseret. Though, like after the Utah War, a compromise on statehood might be reached much later.
On an unrelated note, can someone please explain to me what is up with the Kadyrovites? Every single piece of combat footage from them I've seen has them fighting like absolute shit. Lots of blind firing and spraying and praying. Like, marginally better than the Afghan National Army was doing back when we were supposedly training them.