Tighter physical and border security may encourage terrorists and extremists to try to use other types of weapons to attack the United States. Persistent Internet and computer security vulnerabilities, which have been widely publicized, may gradually encourage terrorists to develop new computer skills, or develop alliances with criminal organizations and consider attempting a cyberattack against the U.S. critical infrastructure. Cybercrime increased dramatically between 2004 and 2005, and several recent terrorist events appear to have been funded partially through online credit card fraud.