Yes now remember my driver in Singapore was once telling that in Singapore everything is just imported even water.... That time I didn't realise that even water flows from Malaysia..... But suppose if Malaysia does this in reality will there be a war? What will be the reactions of bigger powers like China and USA who are Singapore allies..... Any idea?
Singapore defense strategy is to invade some small part of Malaysia that become the source of the fresh water for Singaporean if war is break out and Malaysia cut the fresh water supply.
--------------------------
When Soekarno attack both Malaysia and Singapore, USA do nothing, despite Indonesia during that time sided on USSR and CCP of China. China also do nothing and support Indonesia case.
During that period where the term is "Ganyang Malaysia", Indonesia bombed Singapore 50 times and attack Malaysian part of Borneo island which has direct border with Indonesia's Kalimantan island. The ones that helped Malaysia/Singapore is Commonwealth nations (Britain, Australia, New Zealand, Gurka from Nepal).
Australia for instant still put their fighters squadron in Malaysia until 1990 despite Indonesia has been under Soeharto that has opposite foreign policy compared to Soekarno. Soeharto for instant helped Malaysia to fight against their communist insurgency in Malaysian part of Borneo island by sending our Army special force, Kopassus.
--------------------------
At this time, I think no one wanting to have a war with another country in SEA. Invasion is near impossible, only Indonesia and Vietnam in SEA that has made invasion to their neighbor. Both nations are newly industrialized countries now, relies on foreign trade and investment to grow the economy and relatively have huge untapped land. Very stupid move to invade other country. Near zero both of them wanting to do invasion. Indonesia democracy and Vietnam responsible Communist Party IMO will make what happen in Russia difficult to happen in SEA.
-----------------------------
If Malaysia attack Singapore, IMO Britain/ Australia/ and possibly India will help Singapore. Both Britain and Australia can make Western countries do sanction on Malaysia. I dont know if Singapore has some kind of defense treaty with USA like happening between USA and Philippine.