World military expenditure is increasing along with global deaths due to armed conflict reaching its highest level since 1995 in 2022.
This is due primarily to the Russian Invasion of Ukraine the deadliest armed conflict in the world. Interestingly, deaths due to armed conflict follow the rank-size rule, as we observe in cities. The Russian Invasion was unprovoked, unlawful, and has killed countless civilians. It’s a very simple conflict. The only solution to the war that will end is for Russia to leave Ukraine. We have tried every other option. List of ongoing armed conflicts
The Arab-Israeli war will continue until Palestinians have citizenship in a UN member state. Over the last few years here on my blog, I have written about my research on the history and politics of the conflict. It is caused by one thing, which is that Palestinians are denied citizenship in a UN member state. The easiest way to describe it is in this decision tree: 
This shows why a one-state solution is probably the most viable path to peace. The far-right parties in Israel and Palestine will be at each other’s throats for mutual benefit in order to scare their population to vote for them. It’s revolting. This is why Hamas is still in control of Gaza and will remain in control of Gaza for the foreseeable future.
The only way a war is possible in a one-state solution is for Hamas and Likud to form a coalition.
The remaining wars are in countries in the high inequality-high corruption-high poverty trap. Solve that trap for those countries and the fighting will cease.
On top of this, there are only a few countries in the world that are really able to project violence at the scale we have seen from Russia. If we filter even further to be a large authoritarian regime bordering a democracy or hybrid regime country where the authoritarian regime has more than twice the GDP per capita and a larger military expenditure than their democratic neighbor there are only three targets, Mongolia, Georgia, and Ukraine. These countries are threatened by Russia and Mongolia by China.
Only two authoritarian regimes today have over 100 million people, Russia and China.
China is (was?) substantially constrained by trade. Invading Taiwan would destroy their economy, bringing in a people’s revolution to overthrow their communist regime.
If we reduce our threshold to countries with over 10 million people and over $10k GDP per capita, we only have Saudi Arabia and Venezuela as potential candidates. As predicted, Saudi Arabia is waging a proxy war in Yemen against Iran while Venezuela is threatening to take 3/4 of Guyana’s land. The rest of the world’s authoritarian regimes are too small or too poor to successfully wage war.
The rest of the Gulf States are slightly less likely to wage war based on their democracy index, but they do sponsor terrorist groups outside their borders to project their ideology even if they don’t have the population to wage war as Russia does.
We need to continue to constrain China with trade to guarantee economic destruction if they invade Taiwan. It has worked so far. We need to further increase sanctions on Russia and increase military aid to Ukraine so Ukraine will be able to fully win the war, and then bring Ukraine and Georgia into NATO as soon as possible. That’s how we guarantee peace in the world.
We can bring peace to the world through a combination of trade through complex interdependence theory, backed up by mutual protection pacts so if any democracy is attacked there will be swift action to counteract the attack.
This is already the case as seen in this map which shows which countries currently have military alliances with the United States. If any of these countries were attacked, the United States would immediately be at war. Israel is the only country with a democracy score over 7, a population over 1 million people, and a GDP per capita over $10,000 that does not have a mutual protection pact with the United States or is a member of the European Union or Schengen Area.
However, Israel has a lower Corruption Perceptions Score than most US allies. At a corruption perceptions score around 60 and below it is less likely the United States will form a mutual protection pact with a country. Israel is right at that cusp. 
Taiwan has a great democracy score and a good enough corruption perceptions index score but lacks recognition from the United States, so they don’t have a mutual protection pact with us.
Singapore’s democracy index score is around 6 which is the point where the probability of a country having a protection pact with the United States is a tossup.
When it comes to Ukraine and Georgia the people have made it clear what they want. The best thing to do is to let them into NATO and assist them as much as they want with implementing anti-corruption efforts to align with the European Union acquis. It’s the same with every other country which chooses this path. Bosnia, Moldova, Kosovo, and Serbia are in a similar situation. Every other European country except Andorra is a member state of the European Union, Schengen Area, or NATO. Andorra is a very special case.
The rest of the world
Enough about Europe, what about other regions?
When it comes to the Americas, Latin America is mostly middle-income and very isolated from any potential threats. Most countries in Latin America are still part of the Rio Pact. The Caribbean islands are too small to make invasions worthwhile. They are safe.
African countries uniformly score poorly on corruption, with Botswana and Mauritius leading the pack with average scores of around 50. No country in Africa has a nominal GDP per capita above $10k. South Africa is the largest country with a democracy score above 5, and they are so far from everywhere outside of Africa that they would be the last place to be invaded. It’s unlikely there will be invasions in any democracy in Africa. There are far better targets elsewhere.
In Asia, India is so populous that invading them would be suicide. Indonesia is only made of islands, so it would be practically impossible to successfully invade. Malaysia is the tip of a long peninsula and you would have to get through Thailand first, which has a mutual protection pact with the United States. Singapore is small and you would have already invaded Malaysia and Indonesia so an invasion of Singapore is basically impossible. All of these countries are members of ASEAN who would almost certainly come to each other’s defense. Mongolia is the only democracy in Asia at risk of invasion.
The only country in Oceania without a US protection pact and a population of over a million is Papua New Guinea. They have a very low corruption score leading to a very poor economy. Australia and New Zealand are protected by ANZUS. Every small island country maintains a very strong relationship with one of the three ANZUS nations. There are no good targets in Oceania.
So, for a country to be a good target for an attack, they need to be:
- Large enough to be worthwhile. No one is going to spend the resources to invade Liechtenstein. It’s not worth it. So you need over a million people.
- No protection pact with the United States. No membership in any other mutual protection pact like the European Union or ASEAN. No membership in Schengen.
- Countries that have low democracy scores are likely to self-implode before they are invaded. They tend to be so poor that they are not worth invading. So to be a target you have to be democratic enough that there is something worth taking.
Ukraine hits all of these targets. Its economy was growing rapidly before the invasion. It is democratic. It borders Russia. It has no mutual protection pact. Georgia and Mongolia are the only other countries that face the same level of danger due to their politics. Taiwan faces a threat from the People’s Republic of China due to its claim, but the Communists are constrained by trade with the United States.
It all comes down to this conclusion.
If you want world peace, defeat Russia.