It is significant in that the US is responsible for its' citizens welfare, i.e. for Americans. If an American is murdered, the US should do all that it can to bring the murderer to justice.

The US has insisted on this for Abu-Akleh , but seems to not care if Jewish Americans are killed by Palestinians. The assumption being that either Israel will take care of it, or that the US doesn't expect much from the PA to be able/willing to punish the murderer.