Israel and the United States have postponed a major joint military drill scheduled for spring, Israeli public radio reported, saying budgetary constraints were behind the delay. The radio, citing military sources, reported that the exercises, codenamed "Austere Challenge 12," would be pushed back to the end of 2012. Despite the postponement, there were no changes to a visit to Israel by top US military chief General Martin Dempsey, scheduled to arrive later this week for meetings with Israeli Defense Minister Ehud Barak and Chief of Staff Benny Gantz. The postponed military exercises were to include thousands of American and Israeli soldiers in the largest missile defense manoeuvres ever held by the allies. They were to be staged at a time of spiraling regional tensions over Iran''s suspected nuclear arms program, but Israel''s army insisted last month they had been planned in advance and denied they were related to Iran. "The exercise scenario involves notional, simulated events as well as some field training and is not in response to any real-world event," the military told the (AFP) news agency. "The US European Command and the Israel Defense Forces periodically conduct routine exercises in Israel. These exercises, which are part of a long-standing strategic partnership, are planned in advance and part of a routine training cycle designed to improve the interoperability of our defense systems," it said. But at a time of tension over Iran''s nuclear drive, which Israel, Washington and much of the international community believes masks a weapons drive, the exercises were seen as sending a clear signal to Tehran. The postponement, attributed to budgetary constraints, also comes as media reports suggest disagreement between Israel and Washington over a possible military strike on Iran. Israel and the United States have a longstanding strategic alliance and are jointly developing the Arrow anti-ballistic missile system. In November, the Israeli state staged a major civil defense drill in the Tel Aviv region aimed at simulating a response to conventional and non-conventional missile attacks.