The comments come as disquiet grows over the quickening pace of China's land reclamation programme in international waters, including its construction of a runway long enough for large military planes.
"If there was a vacuum, if the United States, which is the superpower, says 'we are not interested', perhaps there is no brake to ambitions of other countries," Aquino told an audience of business leaders in Tokyo when asked about China's rising might and the role of the US in checking it.
"They tested the waters and they were ready to back down if, for instance, in that aspect, France said (to back down).
"But unfortunately, up to the annexation of the Sudetenland, Czechoslovakia, the annexation of the entire country of Czechoslovakia, nobody said stop.
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"If somebody said stop to (Adolf) Hitler at that point in time, or to Germany at that time, would we have avoided World War II."
"At what point do you say, 'Enough is enough'? Well, the world has to say it - remember that the Sudetenland was given in an attempt to appease Hitler to prevent World War II," he told the New York Times last year.
That provoked fury in Beijing, which labelled the Philippine president "amateurish", "ignorant" and "lame".
Aquino's comments today come after US President Barack Obama this week weighed in on the growing tensions in the South China Sea, urging regional powers -- particularly China -- to respect the law and stop "throwing elbows".