Small boy just rattling his mouth off. Sing is very small. There is no land mass for defence in depth, scorched earth and tactical withdrawal. Unlike Russia. So defence is how you want to define it. You still need soldiers and arms to keep others from getting ideas of sending in their troops and taking over. See what happened to ex-Portuguese East Timor when the Portuguese left.
Many people and PRs in Sing are very rich. When they are very rich, the world is their oyster.
They effectively become world citizens. They can go anywhere and easily get PR/green card or whatever. So these who are used to a life of luxury are unlikely to risk getting wounded or die fighting for Sing. Have to be realistic about this.