The Six Day War was triggered by Israel launching a breathtakingly successful attack upon Egypt and Syria. This was something Israel was very proud of accomplishing at the time. Why people feel compelled to lie about it now is most curious. The war's origin was in Soviet disinformation. Fraudulent intel given Egypt and Syria that Israel was planning to attack them. Given the history of the Sinai war in 1956 the information seemed credible. Both Egypt and Syria ratcheted up tensions with statements. Israel responded in kind. The closure of the Straits of Tiran was just part of the pattern of antagonistic behavior on all sides. Israel mobilized it's reserves. Prime Minister Levi Eshkol knew Israel could not stay mobilized for a long period because of economic reasons and was persuaded to order a war he did not really want. The 'trigger' was the cost to the economy of maintaining a high level mobilization of the IDF.
U.S., allies conduct 1 air strike in Syria and 11 in Iraq against ISIS militants (Reuters)
from the article: Tension with Syria can turn into war in an instant