With Tuesday’s attacks, Abu Musab Zarqawi, a Jordanian militant with ties to al-Qaida, is now blamed for more than 700 terrorist killings in Iraq. But NBC News has learned that long before the war the Bush administration had several chances to wipe out his terrorist operation and perhaps kill Zarqawi himself — but never pulled the trigger. ...... Military officials insist their case for attacking Zarqawi’s operation was airtight, but the administration feared destroying the terrorist camp in Iraq could undercut its case for war against Saddam.