system
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human
[MCU] How do you lose a Chitauri Leviathan? - those giant alien space whales (spoilers)

The Chitauri invaded Earth at only one point... downtown Manhattan, New York City, 100% American soil and SHIELD jurisdiction.

From the Marvel One-Shot Item 47, we know that Chitauri technology was jealously tracked by SHIELD, as is all alien technology by the Agents of SHIELD in their pursuit of 0-8-4 codes.  It is easy to count the number of Chitauri Leviathans that fell in New York and Item 47 shows tracking is even more granular than that.

Chitauri Leviathans are the size of a small city block (not to be confused with a New York City block) and without being disassembled, can't be lifted by any operating human technology known to man *except* SHIELD helicarriers.

**How do you "lose" an entire Chitauri Leviathan in Sokovia?**

From TWS, we know HYDRA has infiltrated SHIELD, however, we also know there are still loyal SHIELD agents at the highest levels.  How does an entire Leviathan take a ride on a helicarrier to Sokovia without coming to the attention of a single loyal SHIELD agent?

How does HYDRA justify taking a helicarrier and a Leviathan outside of the USA to Sokovia, never to be seen or heard of or return again that doesn't either immediately blow their cover or bring Sokovia straight to the top of SHIELD's suspect-list once HYDRA is blown?  When HYDRA is blown, why isn't recovering a giant city-block's worth of alien tech which rivals the significance of a helicarrier a top priority to the top-brass compared to tracking an Obelisk that is just one-of-many?

From AoS, we see that helicarriers are such valuable assets the orders are to blow them up rather than allow them to fall into enemy hands... and that's mundane Earth tech that anyone can replicate... a Leviathan can- and does- allow HYDRA to take its minions to another level.  HYDRA having an active working helicarrier (capable of moving a Leviathan) would absolutely be unacceptable and a top-priority target, so that suggest the Leviathan wasn't moved *after* SHIELD fell.

So how can you possibly disappear a Leviathan that doesn't get called into question or isn't immediately traceable afterwards?  Fury's Toolbox seems to know what Coulson had for breakfast... how does it lose alien tech of that scope and size?

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Regarding the ridiculous "can't count" argument.  There are several times to establish a count and the count isn't that high.  The Leviathans were kept in control by three Avengers alone.  There weren't that many of them.  Their appearance was heralded by a beam of light into the sky in one of the most densely populated cities in the world in a era where everyone has a camera.

Count #1 is of anything coming through the portal which would be remarkably easy to aggregate a correct count on.

Count #2 is after the battle when all those Leviathans fall from the sky, they do accountable property damage and remain there, static, for a good amount of time.  Time for them to be recorded by civilians, by Tony, by satellite, by aerial survey, by many reliable means.

Count #3 is when SHIELD is tasked to extract these Leviathans from NYC at all speed so that normalcy can resume.  When there is an available and operating technology that can actually grant NYC relief from the giant corpses of Leviathans stopping recovery, there's no way the helicarriers stand idly by or have them be removed by some slower laborious effort.  When those Leviathans are moved there's going to be a count.

But... somehow, SHIELD can't count.
gpt
Easy. You bury the facts underneath a mountain of minutiae and meaningless acronyms. SHIELD has multiple covert research bases across the globe. HYDRA, via Secretary Pierce, obfuscated the storage sites of recovered Chitauri tech so that the most valuable ends up at Sokovia.