These two cases probably don't quite fit what you're asking, since they don't involve particular species being used deliberately as weapons of war or revenge. However, I think they're relevant all the same, for they illustrate how conflicts between groups of humans also involve what the historian Alfred Crosby called "portmanteau biota"--that is, the species necessary for human existence.

One example is the shift from buffalo to cattle on the American Great Plains. For the native American groups living on the plains, the buffalo were their livelihood, providing the foundation of the economic life. At an ecological level, the prairies can be thought of as great solar-powered engines: sun and rain combined to generate oceans of grass. The buffalo then transformed that grass into things meaningful to humans: meat, hide, and other useful materials. Anglo-Americans understood this perfectly well, and when they elected to expropriate and in many cases exterminate Native Americans, they attacked not only their human opponents, but also the buffalo as well. Andrew Isenberg's The Destruction of the Bison details this process, and how it transformed the ecology of the Great Plains. The sun and rain remained the same, but Anglo-Americans replaced buffalo with domesticated cattle: faster-growing, more manageable, and more marketable thanks to the cultural significance of beef. To some extent, this also resulted in a change in grass species, although that may have preceded the cattle, and it may have been less intense on the prairies then elsewhere (like California) because there were already large herds of hoofed ungulates grazing. In some places irrigation allowed Anglo-Americans to replace the native or invasive grasses with cereal grains--also essentially species of grass--like maize, wheat, and barley.

Another example of species accompanying human conflict is in New Zealand. There, the European black rat displaced the smaller New Zealand rat as English colonists settled, increased their presence, and eventually came to dominate the islands. Alfred Crosby's Ecological Imperialism has a chapter on this phenomenon, and he describes how the change in the islands' dominant rat species was obvious to people on both sides.

I'm not familiar with the use of invasive species for this purpose, but this likely falls under the international legal concept of "ecocide."

The use of depleted uranium shells or phosphorus munitions are commonly referenced in this context as is the most famous example of Saddam ordering the sabotage and lighting of the oil well heads as his troops withdrew from Kuwait.

The ecological devastation by Saddam is unparalleled and done purely out of spite. The Kuwaiti Oil Fires constitute the largest "oil spill" in history.

If you were to focus your research on ecocide, you might find some evidence of intentional exportation of invasive species.