Two recent rounds of US/Israeli talks about the sale of Lockheed Martin F-35s to the Israeli air force have ended with the same gap that has so far prevented the signature of a letter of agreement.
The talks are to resume in May, with Israeli sources saying that "more time and goodwill is needed before an agreement can be signed".
Discussions have centred on major issues, including the extent to which Israel will be allowed to install its own electronic warfare systems in the stealth fighter, and the extent of industrial co-operation for its companies.
The Israeli air force is also objecting to a plan to send systems or complete aircraft to a European support centre, most probably in Italy.
These matters and others will be discussed during the next round of talks, says the defence ministry. "There are some issues to be discussed and there is an effort to reach an agreement . This will take time."
A so-called Security Cooperation Participant on the Joint Strike Fighter project, Israel is expected to sign an initial deal to acquire around 20 conventional take-off and landing F-35As.