TOKYO - Japan's Self-Defense Forces will raise the alert level at bases across the country following the death of al-Qaida leader Osama bin Laden, who Washington said had been killed by the US forces in Pakistan.

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Defense Minister Toshimi Kitazawa told a new conference Monday that the decision was made to guard against any possible reprisals.

"We can not presume what could happen in terms of retaliation, but we want to boost the frequency of patrols at camps and bases," Kitazawa was quoted by local media as saying.

US President Barack Obama announced Sunday night that a US operation had killed bin Laden outside Pakistani capital Islamabad.