Today's language lesson: "Ensure"

A lead article in today's Los Angeles Times, discussing Iraqi anger over long detentions in Iraqi prisons by American forces, tells us:

"The military has established a multitiered system to ensure that innocent people caught up in chaotic events are not held for extensive periods."

Really? From Dictionary.com:

Ensure: To make sure or certain; insure

Ensure? The very next two sentences in the article give the lie to that claim:

"Records provided by the military, however, show that the evidence against suspects justifies prolonged detention in only about one in four cases. Nonetheless, more than half are held three months or more before being freed."

And some, we might add, are held for years.