How Can A Country Defend Itself From A 10 Times Bigger Population Outside Threat

On what factors does the economy of a country depend?

Natural resources Geography-especially proximity to the sea and the overall landform with respect to how easy it is to build things, produce crops etc. Existence of an effective criminal justice system, functional political institutions to defend the country from outside threat, to what extent the political institutions recognise individuals' property rights and defend them. The policies undertaken by the political class (henceforth referred to as the government) about the economy. Being the small government proponent austrian-libertarian I am, I will want the government to be small but effective. But I recognise some minimal government measures when an economy is being built from the scratch (e.g. Germany, Japan right after WWII). However, it is also equally important for the government to step aside as soon as some sanity returns. A lot of people will cite things like tradition, or social psychology of the population as whole as another factor. But I believe they will be dependent on the previous factors. In addition, if people are given freedom to decide their individual fates (instead of the government meddling in) then ultimately the whole world will be pretty much homogenised on these aspects, rendering them less and less important.

Why is it that a country like Pakistan, which is weaker than India, still able to project itself as a threat?

The underlying narrative in Pakistan is that India is an existential threat to Pakistan. But India has never attacked Pakistan.Let us see some rankings of Pakistan - 5th Largest Country by population, 6th largest Army, 7th country to have nuclear weapons, 13th rank in Global Firepower Ranking, 42nd largest economy (nominal GDP), 66th rank in terms of receiving FDI, 72nd rank in Foreign Reserves ( but IMF says that Pakistan has negative reserves), 66th rank in list of exporters.Apart from population and military ranking, Pakistan is outside top 40 in most economic indicators. Former PM Bhutto once told in 70s that - We(Pakistan) will eat grass, even go hungry, but we will get one of our own (Atom bomb). This sums up the desire of Pakistan to have a strong military and ignoring other aspects of the country. A child born in Nepal has more chance to go to school and complete education than a child born in Pakistan. More than 40% revenue of Pakistan goes into existing debt servicing.It is often said Army in Pakistan needs a state to protect it's privileges. If a big country is so determined to have a military power ignoring it's economy then it would certainly become a threat to a bigger power like India.

What would happen if Malaysia and/or Indonesia invaded Singapore? Would Singapore be able to defend against the invasion? What's the implication of this scenario?

With all due respect. If malaysia and Indonesia joined forces to destroy singapore. They will easilly do so. Indonesians have 210million population, a fierce army (although equipment is outdated). Singapore only has around 3-4 mio tops, and that numbers includes kuniangs, elderly, kids, the rich (who probably be the first one to flee), good paid employees with many things to lose, etc.Singapore would be a small red dot, if both indonesia and malaysia carpet bombed singapore, or launch a few ballistic missiles every missile would be a hit since every inch of singapore is densely populated.Sure singapore will hit back and hard but sorry, realistically speaking without nuclear or wmds the odds are too big. Even when malaysia and indonesia stupidly makes blunder in the war on the grand scheme of things the numbers and casualty would be something that's out of the question for Singapore.Singapore might retalitate in johor but they have not enough manpower to secure it, best case scenario they can strike back and hold johor, kl, Jakarta, batam, that's 4 major cities with millions of occupat. Jakarta alone has 12m population. How does singapore find enough people to control the city? One guy has to watch and control 10 people, and that is if you include the kids the women and the elderly. The war on attrition would be hugely against singapore as for 1 singaporean has to fight against 50 indonesian plus 15 malaysians.The only question is at what cost?Although luckily i dont think this will happens. Singaporean wont surrender, foreign nation would intervene, sanctions, the us will play their parts, and the actual prize of Singapore is her people, if you invade and kill everyone inside singapore is nothing but a piece of worthless land which malaysian and indonesian has plenty of.EDIT: I’ve lived in Malaysia/Indonesia/Singapore for a time, and I have no hate/favor towards one another, and this war will never break out in real life, but in quora universe, with the assumed constraint (No Outside interference, no WMD) there’s not a chance Singapore could win. The only question will be how much of the enemies they take down with them before the city falls.