It is not the first time a "secret" trip has been scuppered by foreign politicians - Iraq's Prime Minister Haider al-Abadi put photos of himself and Prime Minister John Key on his Facebook page while Mr Key was still in Iraq visiting troops last year.
That mishap was partly because delays in Mr Key's travel meant he was in Iraq longer than expected.
The reasons for the Defence Force's insistence on secrecy for Mr Brownlee's Israel trip are less clear.
Similar secrecy has not applied to visits to Israel by Foreign Minister Murray McCully, who visited in 2015 as part of his efforts to get a Security Council resolution on the Middle East peace process, and did media interviews while in Israel.
Israel has been critical of New Zealand for trying to spearhead that process and it was put on ice until Mr McCully recently revived it.
It is understood Mr Brownlee's visit was not related to that effort. Mr Brownlee's visit came after Mr McCully repeated his criticism of Israel for land occupations in the occupied Palestinian territories, which he said threatened the viability of the two-state solution.
Isis foes to discuss next move
Defence Minister Gerry Brownlee is heading to Europe for a meeting of defence ministers in the coalition to counter Isis as debate begins about what New Zealand's next steps will be.
The meeting in Germany will be led by US Defence Secretary Ash Carter.
In March, Mr Carter wrote to all 65 coalition countries asking them to contribute more to the fight.
New Zealand's deployment of about 145 troops to Iraq to help train Iraqi forces is due to end next year.
Labour leader Andrew Little said it was clear on his visit to Iraq last week that coalition countries wanted New Zealand to do more.
"It was made pretty clear the expectation is that more is needed and more needs to be provided."
