The Haitian case was:UN sets out food crisis measures
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Mr Ban said export restrictions and import tariffs ought to be minimised to alleviate the crisis.
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BBC NEWS | Special Reports | UN sets out food crisis measures
that they minimised the import tariffs;
that cheaper products came into the market;
and that the price rise caused the riot.
The Japan's case, so far...
1. Japan protects the rice market and agreed with so-called minimum access from the rice exporting countries, mainly from the US.
2. The majority of rice has not been consumed, but stored.
3. A bureaucratic choice would be possible to keep importing the rice. But I don't know if it is a right one under the current crisis.
It is good for Japan to announce that we will release the storage to other countries to ease the crisis. But it is a merely temporary relief after all.