What if it's further encrypted beyond that, to avoid interception?

After each attack they had to return to low level to avoid interception by MiGs.

The airplane left on April 13, 1942, and managed to avoid Japanese interception.

The other four are running silent to avoid interception.

With the advent of guided air to air missiles, bombers needed to avoid interception.

The raids were usually carried out at night to avoid interception.

It is possible, they said, that the Russian order was issued earlier to avoid interception by the United States.

They'd been specifically ordered not to bring cell phones, to avoid interception by enemy signals intelligence.

These bombers retained their defensive armament, which was vital since they were unable to avoid interception.

High-altitude flight would still be useful to avoid interception by aircraft, but did little to help against missiles.