That’s why it’s disheartening to hear fellow Republicans, such as Sen. Rand Paul (Ky.), suggest that our nation should ignore what’s happening in Iraq. The main problem with this argument is that it means ignoring the profound threat that the group now calling itself the Islamic State poses to the United States and the world.

In the Islamic State, which came to prominence in Syria and now controls ample territory, weapons and cash in both that country and Iraq, the world is confronting an even more radicalized version of Islamic extremism than al-Qaeda. This group is well-trained, technologically sophisticated and adept at recruitment, with thousands of people with European passports fighting on its side, as well as some Americans.

This represents a real threat to our national security — to which Paul seems curiously blind — because any of these passport carriers can simply buy a plane ticket and show up in the United States without even a visa. It’s particularly chilling when you consider that one American has already carried out a suicide bombing and a terrorist-trained European allegedly killed four at the Jewish Museum in Brussels.