If cyber terrorism can be defined as the use of technology such as the internet to inflict fear and loss of liberty with political objectives then I would say the potential already exists in federal databases and bureaucratic agencies to arrest people expressing sentiments and viewpoints opposed to government policy decisions. The first step in making this nightmare a reality is to dismiss the possibility by assuming such a thing could never happen in America because the general public will always overwhelmingly support free speech.
The threat of cyber terrorism will always pervade our society. Cyber terrorists operate in the shadows and they will not hesitate to strike when they want to. They can attack our badly prepared infrastructure or design mechanisms. I think that the terrorists will win because our software has not been updated.
The United States, like any powerful country in the modern world is always at risk from threats such as cyber-terrorism from rogue nation states such as North Korea, tech-savvy international terrorist organisations such as Daesh and individuals associated with groups such as Anonymous. These attempts are inevitable but the United States government repels such attacks regularly and is on the cutting edge of anti-hacker technology. Therefore, it is unlikely that a cyber-attack will be able to cause catastrophic damage even if it was successful.
From everything that has been written on this topic, it is apparent that the United States government is vulnerable to cyber terrorists. Although there is a lot of security in place, hackers are good at what they do and can attack the United States. The government constantly works to eliminate threats, but it's a real possibility.
Cyber terrorists could decide to attack at any minute and shut down vital systems. I don't know to what extent things like the Treasury or big banks are at risk, but there are many ways cyber terrorists could attack our country. Things like our water supply are online there, they could choose to start there to incite panic.