The Ukraine Situation - sort of like Konfrontasi.

When Singapore, Sabah and Sarawak (and also Brunei, but they later withdrew) wanted to join the Federation of Malaya in the early 1960s, Indonesia was against the proposal. And when the Federation added these 3 states in 1963, Indonesia initiated Konfrontasi. 

Have you ever asked, "why Konfrontasi?" WTF does Singapore joining the Federation of Malaya got to do with Indonesia, right? 

Because Sukarno (then president of Indonesia) had a vision of a Greater Indonesia, one similar to the old empire (Majapahit, I think). Similarly, Putin has ambition (or vision, or delusion) of the old Soviet Union where Ukraine is "My Kraine".

So now Ukraine (like Singapore in early 1960s) wants to join NATO (analogous to Federation of Malaya), possibly eventually, joining the EU, but that's another story. Russia (analogous to Indonesia during Konfrontasi) wants Ukraine for herself, and objects. And the threatened invasion is similar to Konfrontasi, except Russia has quite a bit more capacity to prosecute a war than Indonesia in the 1960s. So if Russia objects militarily, it would be a lot more than a few saboteurs sent to Ukraine.

Why Konfrontasi?

[Edited, 1/4/2022]

If you search "Why did Konfrontasi happened?" you will get some "official" answers.

If you are like me, you would be dissatisfied with the answers. 

Officially, this is Singapore's sanitised history:

Konfrontasi (or Confrontation, 1963–1966) was Indonesia’s response to the formation of the Federation of Malaysia, arising from the British decolonisation process in Southeast Asia. Konfrontasi involved armed incursions, bomb attacks and other subversive acts aimed at destabilising the states that were to be included in the Federation, namely, Singapore, Malaya, Sarawak, Brunei and North Borneo (now known as Sabah).
When the concept of Malaysia was first mooted publicly by Malayan Prime Minister Tunku Abdul Rahman in May 1961, the Indonesian government initially did not raise any objections. It began to express opposition to the Malaysia proposal shortly after the Brunei Revolt of December 1962.

You may be satisfied with the above. Or you might dig deeper. Like what were the basis of Indonesian objection or opposition to the formation of the Federation? Further along, you read:

Indonesia criticised the Malaysia plan as a British “neo-colonialist project” and a threat to their country’s security. 

Which is diplomat-speak for "because I don't like!"