The Space Race was high-pressure, but placed a relatively high emphasis on safety on the US side; and even the Russians were doing their best to make sure missions didn't fail too often. A government sponsored effort would place a high emphasis on making sure the source and details of the project weren't leaked in way that could be copied easily (which is already a degree of safety), and it would have the resources available to take any security measures that wouldn't slow things down tremendously.

Most DARPA/Military research projects do receive extensive testing and attempt to ensure reliability. Even when it's done poorly, or unsuccessfully, it's a huge consideration in development.

But yes, there would be a certain level of urgency, which might keep them from waiting for the best possible security. Which is why intermediate approaches grounded in a existing (or technology we can extrapolate will be existing) technologies.