A terrorist attack just happened in my city

For some quick background, Chechnya is a republic of Russia bordering the country of Georgia (formerly a Soviet Republic). They have historical grievances with Imperial Russia, Soviet Russia, and modern Russia. As the Soviet Union dissolved, some countries were granted sovereignty and independence (Ukraine and Georgia, for example) while others received a status as a more autonomous republic within Russia.

For reasons unknown to me, the Chechens found themselves on the Russian side of the new border with Georgia. Although an independence movement was attempted, the Russian government rejected it. Separatists and others engaged in an insurgency initiating the first civil war beginning in 1994. Political violence, general instability, and religious extremism contributed to a protracted insurgency. The Second Chechen (Civil) War stretched into the late 2000s. During this time Russian forces committed a variety of human rights abuses, and I'm not saying one group is more at fault than the other here, but there is video from one of these wars of Russian forces intentionally targeting Chechen towns for artillery target practice. Tens of thousands of civilians of varying backgrounds and affiliations were killed during these wars.

In 2002, a group of Chechens took hostages at the Moscow Theatre. The Russian's military and police response was harsh and catastrophic and painted a picture for the west of the kind of brutality that the Russian government remained capable of. About two years later a Chechen group demanding independence took over a thousand hostages at a school. The event ended badly for everyone and the result that was the newly elected president of Russia, Putin, used the opportunity to reduce autonomy of some regions and consolidate power for himself.

Ramzan Kadyrov, essentially a Putin-backed warlord, received control of Chechnya after his father's death (his father had switched sides and betrayed the Chechens). More recently, Kadyrov's army participated in the invasion of Ukraine on behalf of Russian forces, complete with a bunch of Instagram posts.

On a somewhat related note, in the United States in 2013, the Boston Marathon bombing was perpetrated by two youths living in the U.S. who claimed ties and some amount of motivation from their Chechen ancestry, even though they'd never been to Chechnya, but mostly on western involvement in Iraq and Afghanistan.

So it's safe to say that there are some historical grievances here and like in many parts of the world, not a lot has been done to properly address them and find a lasting peace.

Gassing the hostages.

Or keep going from bad to worse and shoot thermobaric missiles at a children's school with the children still in it.

Russian response to terror is to nuke and pave.

I can't do it justice what happened there so please do read up on these instances. @ChingShih already mentioned both events, but the articles go in depth about the ridiculousness of the Russian response.