JERUSALEM -- A former Israeli spymaster says if he were an Iranian, he would be "very worried" by Israel's talk about possibly attacking Iran's nuclear facilities.

Ephraim Halevy says the next 12 weeks will be "very critical" to Israel's decision on whether to strike. Halevy told Israel Radio on Thursday that if the Iranians "continue to play their games" in nuclear talks with world powers, they're underestimating Israel's resolve.

He says the Iranians' "math is off if they think they have open-ended immunity" in these talks.

Iran contends its nuclear program is peaceful and designed to produce energy. Israel considers Iran a threat to its survival and says Tehran's nuclear program is a cover for bomb-making.

Prime Minister Benjamin Netanyahu said earlier this week that Israel hasn't decided whether to strike Iran.