In 2011, Japan experienced one of the worst earthquakes in recorded history, which caused severe damage to several nuclear reactors. In the days following the earthquake, radioactive material was released into the atmosphere. Depending upon the wind's direction, neighboring countries could have been affected. Japan alerted neighboring countries of the radioactive releases, complying with:

customary international laws

Explanation:

Customary international laws are guidelines that determine that a country must manage a given situation based on international law, allowing countries that may be affected by that situation to be informed in time to establish their own guidelines for coping with the situation.

When Japan announced to neighboring countries about possible air contamination, it means that Japan has acted within customary international laws, allowing countries that could be affected by this air, to establish their own coping strategies.

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