yes it's yes

As long as the US isn't still neutral.
If US were neutral it would be be allowed to be in a position to enter the Baltic
"In position" /= "enter the Baltic". Besides, the US could not be in a seazone that is less than two spaces from Britain, which means it would not be allowed to be in a position to enter the Baltic in a single move as it couldn't get close enough to SZ 112.
Unless you had a serious typo in there and actually meant the US would NOT be allowed to be in a position to enter the Baltic, which is true.