The year-long rise of ISIS, and its leaders' appeals for supporters to carry out attacks around the world, has authorities on high alert. July 4 security alerts have become almost routine, with authorities warning every year that the holiday could inspire an attack by foreign or home-grown terrorists. But the vigilance surrounding this year's celebration carries added weight. The reason is ISIS. The year-long rise of the radical Islam terror group, and its leaders' appeals for supporters to carry out attacks around the world, has prompted a sharper sense of caution.