If we truely have high-level terrorists crossing borders, then yes, every person's identity should be checked against national police files and thus, when Internet is down, every decision should be suspended, if we want to be consistent.

Obviously I say "if" because those who actually want to deceive the system walk through borders by foot (taking advantage of the terrain), and register as migrants (under no less than 14 identities for one person - that's what happened for the last terrorist in Europe). Heightened passport security rules are great, but they mostly catch citizen who thought they were law-abiding, while it's much, much harder to deal with real criminality.