* Pentagon says exercise will still be biggest ever
* Israeli official says scale meets requirements
* U.S. says cut due to schedule shift
WASHINGTON, Aug 31 (Reuters) - A U.S.-Israeli ballistic missile exercise postponed until this autumn will involve fewer U.S. military personnel than initially planned, the Pentagon said on Friday, but it rejected a media report portraying the decision as a sign of U.S. mistrust.
The exercise is being planned amid rising war talk in the Israeli media and reports that Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak are debating a unilateral attack on Iran to knock out its nuclear installations. Washington has cautioned Israel against going it alone.
“Austere Challenge-12 remains the largest-ever ballistic missile defense exercise between our nations and a significant increase from the previous event in 2009,” said Air Force Lieutenant Colonel Jack Miller, a Pentagon spokesman.
“The exercise has not changed in scope and will include the same types of systems as planned. All deployed systems will be fully operational with associated operators,” Miller said.
Time magazine reported on Friday that initially about 5,000 U.S. troops were planned to be involved in Austere Challenge-12 but that the number was being pared back to between 1,500 and 1,200. It quoted an unnamed Israeli military official as saying the change was a sign of U.S. mistrust.
Miller said U.S.-Israeli ties were strong and Austere Challenge “is a tangible sign of our mutual trust.”
A U.S. official, speaking on condition of anonymity, declined to say how many U.S. personnel would be involved in the exercise but said the reported figures were wrong and the change in scale was far smaller than indicated.
An Israeli defense official briefed on the exercise told Reuters the drill “will be held on a similar scale as when it was last held, two years ago.”
The Israeli official said the size of the exercise initially was slated to be larger but added that “the changes are within the framework of the drill’s requirements and nothing more.”
“These things are planned over a long time and changes are not uncommon,” the official said.
Miller said the exercise initially was planned for May but earlier this year Israeli defense officials approached the United States about shifting the date until the late autumn.
“When the exercise was moved, the United States notified Israel that due to concurrent operations, the United States would provide a smaller number of personnel and equipment than originally planned. Israel reiterated to postpone until late fall,” Miller said. (Reporting By David Alexander and Dan Williams in Jerusalem; editing by Mohammad Zargham)