waterbound, if the US haven't yet lift the ban on Chinese imports, how on Earth you know things have improved with the MIC guns?
Also, unless you're talking about their security details or police at their headquarters in New York, UN has no standing armed forces of any sort, Blue Helmets are those from contributed nations and they bring their nation's issued weapons.
Now on the topic...
India always see arms sales as part of diplomacy so yeah they won't be happy if Vietnam, whom they allied along with Japan to blockade China, instead shop with India's sworn enemy Pakistan, but let's be fair, what Vietnam wants India don't produce (and doubtful if they got the spare capacity, even the order is so small, for one who have to rely on TAR-21 and AKMs to compliment its arsenal).
And that also tell the Vietnam is rather poor...IIRC, MP-5's patent have long since expired so practically anybody can make their copy and H&K can't do squat, other than remind everyone the original is the best - though more expensive. Such a small shipment and one for the police mind you, couldn't do much in any impact of balance...if Vietnam CT unit trains on the international standard, the total of 200 SMGs and 100 sniper rifles might just enough to meet the wear and tear plus a good degree of ready stock, which they should be.