"A number of people who have supported me on the border fence in the U.S. have observed the fences in Israel and their effectiveness"

This quote by Duncan Hunter is referring to the effectiveness of the border fence in Israel. He is suggesting that a variety of individuals who have actually supported him on the border fence in the U.S. have actually seen the fences in Israel and have actually been impressed by their efficiency. This indicates that the border fence in Israel is a successful deterrent to illegal immigration which the U.S. must consider carrying out a similar system. Hunter is most likely suggesting that the U.S. must want to Israel as an example of how to effectively manage its own borders. He is most likely advocating for a stronger border security system in the U.S. in order to decrease unlawful migration.