The signal value was, at best, an extremely minor signal. The shield was never a significant military threat to Russia, which was obvious and well known to both the US and Russia at the time.
The only information it carried was that Poland was choosing the US over Russia, which had also been extremely obvious to everyone for a long time, since they had been announcing it to anyone who would listen for years.
The shield was thus of utterly insignificant value as a signal in terms of Russia's decision to join or not join international organizations. It was a signal to Poland, not to Russia.
The signal value was, at best, an extremely minor signal. The shield was never a significant military threat to Russia, which was obvious and well known to both the US and Russia at the time.
The only information it carried was that Poland was choosing the US over Russia, which had also been extremely obvious to everyone for a long time, since they had been announcing it to anyone who would listen for years.
The shield was thus of utterly insignificant value as a signal in terms of Russia's decision to join or not join international organizations. It was a signal to Poland, not to Russia.