There are three major categories by which The Host and Gojira can be analyzed thematically: monster origin, monster appearance, human response.
The titular monsters are both the unexpected consequences of some horribly destructive act. Gojira was unleashed upon Japan by the nuclear bombings, and the host was a mutant created by the carelessness of an American scientist pouring formaldehyde into the Han river. Both origins are based upon actual events, with the atom bombings and nuclear testing forming the basis of Godzilla and the incident creating the host actually happened in Seoul.
Now their appearances are also influenced by their origin’s and each has its own implications. Gojira is an ancient beast, mutated by radiation to have such abilities as radiation breath which act as essentially small scale atomic bombs. His massive size and nigh indestructible nature make Gojira a clear metaphor for the beast unleashed with the creation of nuclear weapons. Gojira is a metaphor for the threat of nuclear warfare and the destruction it brings, something that could only be properly put onto screen by the only society to live through a nuclear bombing.
The Host similarly acts as an allegory for chemical weapons and biological warfare, highlighted by its mutated appearance. It looks like a fish that has grown terrestrial feet, but only two are fully formed. It’s movement isn’t poised at all, it careens and crashes about, destroying all in it’s wake. It’s very imprecise creature. It uses a long tongue to latch onto people, though it keeps its victims alive for a while before killing them. It’s a massive malformed creature that looks very much like it is something nature could not produce on its own. This ties into it’s origin as a mutated fish at the hands of chemical misuse. It’s erratic nature mirrors the erratic effects of chemical weapons upon people, as does it’s malformed and hideous nature. In addition it’s drawing out of the victims’ deaths is meant to be reminiscent of the slow deaths of victims of biological warfare. In addition much of the film is spent attempting to escape a quarantine put in place to protect the locals from a supposed virus unleashed by the beast.
In both films the human response is a three step process: first the Americans show up and attempt to combat the beast, secondly some horribly new weapon is introduced to combat the monster, and lastly it is the native inhabitants that finally vanquish the monster on their own. In Gojira the army attempts to build a large electric fence that fails to stop beast. This is reminiscent of stop-gap measures that sought to slow down or prevent nuclear proliferation. The Host focuses primarily on the quarantines that isolates the victims for possible infection. This shows how the US treats the Korean citizens as less than people but as problems to be solved, shown in the way they handle moving the mourners from the wake.
Each film has introduces a weapon that has the possibility of doing even greater damage in an effort to destroy the beast. In Gojira it is a device that destroys oxygen and in The Host it’s a chemical known as Agent Yellow which is a thinly veiled reference to Agent Orange. Agent Orange was a supposedly “safe” chemical used during Vietnam that did horrible things to any civilian caught in it’s cloud. In both cases the response is considered overwhelmingly more harmful to the populace than the monster. In The Host, Agent Yellow only stuns the monster, but poisons many protesters, again showing the carelessness of the US Army. In Gojira however, Serizawa acknowledges the destructive potential of his weapon and decides to destroy it. Both responses act as criticisms of humanities assumption that in order to combat dangerous weapons even more dangerous weapons must be created, though one chooses to show the destructive potential while the other acknowledges it and uses it as a basis for the choice to deprive humanity of the device’s plans.
In the end however, it is the locals who inevitably defeat the beast. In Gojira it is the device that vanquishes the creature, but it is a creation of Serizawa, a native, who understands the implications of such a machine, which is why he destroys it later. In the Host, it is the Park family using the tried and true method of burning the monster to death. In both cases it is only through the ingenuity of the native inhabitants that the monster is defeated, affirming the rights of the natives that they can handle themselves without US intervention. They must handle their own problems and not wait on foreign powers to help them.
All three elements work in concert to establish to thematic criticism of the creation of dangerous weapons and the tendency of their makers to misuse them.