Why are you again bringing India in discussion ? Stick to Vietnam..
Okay, let's stick to Vietnam.
So you are suggesting the west to gift billions to them in order for Vietnam to purchase and maintain over 1,000 missiles.
Good, let's say the US and Japan cut off some spending from healthcare and infrastructure to do that while its citizen wondered "WTF?".
And Vietnam became the world's largest missile cache.
Because not a single person had experience operating them.
Surely the US can spare some more and give them the proper training.
Fantastic, Vietnam spent some 1-2 years to make the missiles combat ready while China moved a few SRBMs and cruise missiles around and collected some intel via satellites and stuff to make sure most of them will not fire when a war breaks off.
After that, China maintains the status quo and it is business as usual.
But for Vietnam, there are over 1000 missiles they needed to maintain and have active personnel at all times.
Well, surely the US can cover this cost because the US is so rich that it doesn't care if a couple dozen millions go missing.
So all that billions of spending just turned into a none stop bleed hole in the national reserve's wallet.
(And since Vietnam doesn't have the sufficient R&D capability, after 20 years all these missiles will be non-functioning or obsolete)
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Wait, you think China can just maintain the status quo with Vietnam?
There is going to be a war!
And when there's a war, those 1,000 missiles will be put into good use.
Well if China is not invading Vietnam, the status quo will be maintained.
Unless... Vietnam attacks first.
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Scenario 1: Surprise attack from Vietnam!
Likely Initial outcome: The majority of PLAN's south china sea fleet will be sunk and PLA's military based in the area will suffer losses. No force can stand against hundreds of missiles.
And then PLA's SRBM will suppress missile launch sites, and PLA's army and airforce will move in, and after that we can think about if there will be a country named Vietnam anymore.
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Scenario 2: Evil China invades Vietnam!
-Wait, why would China do that?
-I don't know, because they are evil!
-Okay... I guess.
Trying to use lots of missiles instead of actual army, navy and air force to defend a country has been Taiwan's strategy ever since China gained in upper hand in military strength. And PLA's strategy is developed just to counter that.
So PLA can just use the same strategy against Vietnam. SRBM's against missile launch sites and airfields while marines establish landing sites.
Except... Vietnam shares a borderline with China. There's no need for marines to risk approaching from sea. PLA's massive army can just roll in with some AA support. (Subsonic LACM poses little threat with proper AA)
That doesn't mean the marines will just sit and watch. Vietnam's territory is thin and stretched. One breaking point from the middle will cut of Vietnamese military's supply chain completely.
Before Vietnam knew it, the war has already been lost.
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So why is the US spending billions just to gift Vietnam over 1000 missiles again?