Could a Government Launch a 51% Attack on a Cryptocurrency?

It is theoretically possible for a government to launch a 51% attack on a cryptocurrency. A government could use its resources to acquire a large amount of mining hardware and electricity to control the majority of a network's hash rate.

However, this would be a very expensive and politically risky move. It would also be difficult to keep such an operation secret.

The economic and geopolitical consequences of such an attack could be significant.