"Egyptian aggression initiated the war as Egypt formed a blockade of Israeli shipping in the Straits of Tiran, removed the UNEF peacekeeping forces from the Sinai, and deployed a large military force in the Sinai on the Israeli border. [1] [2] [3] "
thats from the Wiki article on it, but its backed up by these sources.
"In 1967, Egypt ordered the UN troops out and blocked Israeli shipping routes - adding to already high levels of tension between Israel and its neighbours."
Israel and the Palestinians in depth, 1967: Six Day War,
BBC website. URL accessed May 14, 2006.
"In June 1967, Egypt, Syria and Jordan massed their troops on Israel's borders in preparation for an all-out attack."
Mideast 101: The Six Day War,
CNN website. URL accessed May 14, 2006.
"Nasser... closed the Gulf of Aqaba to shipping, cutting off Israel from its primary oil supplies. He told U.N. peacekeepers in the Sinai Peninsula to leave. He then sent scores of tanks and hundreds of troops into the Sinai closer to Israel. The Arab world was delirious with support,"
The Mideast: A Century of Conflict Part 4: The 1967 Six Day War,
NPR morning edition, October 3, 2002. URL accessed May 14, 2006.
those are from the BBC, CNN, and NPR three pretty liberal news companies if you ask me.