The giraffe needs to be protected and the United States goverment, including the EPA and other organizations that help preserve the enviroment and the natural world can help with that. Even though their are no giraffes native to the US, there are still things the US can do to help.
Yes, the United States government has a responsibility in helping a species like the giraffe from becoming extinct. The U.S. is the richest country in the history of civilization, and thus has a responsibility to help the animals of our planet. This is especially true considering the environmental destruction perpetrated by the U.S.
Helping to stop animals becoming extinct is not one persons job, not a country's job, it is everyone's job. Animals like the giraffe are in danger of becoming extinct because of the actions of mankind as a whole and we should be held accountable for the damage we do to this planet. Also as a species privileged with a higher intelligence we should be using to do good for others.
The United States cannot be the police of the entire world. The United States does not have the jurisdiction to go into other countries and tell them what to do. If other countries have animals that do not live in the United States, and these animals go extinct, there is nothing that the U.S. can do.