Jerusalem - A fake news story has touched off a tense Twitter confrontation between nuclear power Pakistan and Israel, widely believed to have a nuclear arsenal of its own, in an episode that underlines the potentially harmful impact of such stories in sensitive global affairsIn an apparent response to a fake story claiming Israel's former defence minister threatened a nuclear attack against Pakistan if it sends troops to Syria, Pakistan's Defence Minister Khawaja Mohammad Asif reminded Israel that "Pakistan is a nuclear state too."Israel's Defense Ministry tweeted back on Saturday, saying the original story on the site AWD News was "totally fictitious."AWD has been identified by fact-checking organizations as a fake news site.Israel maintains a policy of nuclear ambiguity, neither confirming nor denying the existence of an arsenal. Pakistan became a nuclear power in 1998. The countries have no diplomatic ties.There was no immediate reaction from Pakistan to Israel's response.