On Nuclear War
TL;DR: The US's refusal to fully intervene against Russia's invasion of Ukraine, and to a lesser extent the US's continued armament of Israel, significantly raise the likelihood of a nuclear war occurring in the medium-term future (even if not in either of those conflicts).
One of the arguments given for the US not getting more involved in defending Ukraine against Russia is the fear that Russia might use nuclear weapons in response[1]. A similar argument is sometimes tossed around (although less frequently) for why the US continues to give weapons to Israel, even though they generally end up using them against civilian populations or soft targets that could be handled without the collateral damage from a Mark 84 2000-pound bomb, with the idea being that if Uncle Sam doesn't give them a bunch of conventional weapons, they'll be more likely to nuke someone.
Although this might slightly decrease the odds of a conflict going nuclear right now (I can argue either way), it seems to me that it also significantly increases the odds of a conflict going nuclear in the future.
Some background: After the USSR broke apart at the start of the 1990s, Ukraine inadvertently became the world's third-largest nuclear power[2] due to it possessing ~1700 warheads with at least 200 delivery vehicles (ICBMs and heavy bombers). Because neither the US nor Russia wanted another nuclear power to deal with, in 1994 a deal was struck whereby Ukraine would give its nukes to Russia in exchange for 1) Russia promising not to attack it and 2) the US promising to defend it if Russia does attack.
In 2014, Russia invaded Ukraine, specifically Crimea. The US did nothing.
In 2022, Russia invaded the Ukrainian mainland. The US gave limited military equipment but with incredibly strict restrictions on its usage that limited its effectiveness in repelling the invasion. Two of the reasons for these restrictions were 1) Russian threats to respond to US support with tactical nuclear weapons, and 2) concerns that usage of US missiles inside Russian airspace would trigger nuclear strike detection systems and lead to a nuclear response even if the incoming missiles are conventional.
The unspoken message that every nation in the world heard was that if you have nuclear weapons, the western world (and the US in particular) is so afraid of you actually using them that you'll be able to avoid a US response to almost anything you want to do. My guess is that every nation that isn't a nuclear power or a guaranteed protectorate of a nuclear power (e.g., NATO's non-nuclear members) is now investigating whether it can start a nuclear program or otherwise acquire nuclear weapons. Once it can credibly threaten nuclear action, it's shielded against the sort of US military meddling that's characterized US foreign policy since the nuclear age began.
Once tinpot dictators have nuclear arsenals, it becomes inevitable that they get used in some conflict that otherwise would have stayed, while potentially quite brutal, a conventional war. I can't say with 100% certainty that any particular war that's happened would've gone nuclear if some or all parties had been nuclear powers, but I'd be willing to bet that at least one of them would've or will in the future, if nuclear proliferation is allowed to resume.
In order to prevent this inevitability, the US needs to take advantage of its overwhelming economic and military might to strongly communicate to other nations that nuclear threats are not acceptable in the modern age. If a nation threatens nuclear action, that should earn a swift, decisive response. If the threat is in a diplomatic scenario, the response should be in the same arena. If the threat is in the context of an ongoing military conflict, the response should be kinetic (but conventional).
Otherwise, nuclear war will happen. It may start in a corner of the world that most Americans don't often think about, and it may not immediately result in a full-on civilization-ending event, but it will lead the world further down the road of viewing nuclear weapons as valid instruments of warfare, and that's a path we as a species cannot afford to follow.
[1] Coincidentally, Elon Musk, about whom the first post on this blog bitched, was one of the main people to make this argument, but this particular post is actually unrelated to him and his dumb arguments.
[2] This is admittedly a bit debated. I've seen the argument that the bombs in Ukraine's possession weren't technically in an immediately-usable state (as it's a really bad idea to store nuclear weapons in a completely ready-to-use state for a host of different reasons) and so they weren't really a "nuclear power" in the traditional sense. However, even if certain pieces were missing or not fully installed, it wouldn't take a Manhattan Project-size effort to get one of them ready to go. The "difficult" part of building an atomic weapon is obtaining the weapons-grade fissile material, and they had access to that in abundance. Getting access to scientists and technicians capable of making that uranium and/or plutonium go boom isn't difficult, especially not in immediately-post-Soviet eastern Europe.