It[US] cannot end the movement of its sea units in sea zones adjacent to Japanese-controlled territories while not at war with Japan.
While not at war with Germany or Italy, the United States may end the movement of its sea units on the Europe map only in sea zones that are adjacent to U.S. territories, with the exception that warships (not transports) may also enter sea zone 102.
from: http://www.axisandallies.org/forums/index.php?topic=33001.0