Iran is trying to strike Israeli targets around the world in a bid to stop the assassinations of its nuclear scientists, the head of the Shin Bet security service, Yoram Cohen, said Thursday.

Lecturing at a closed forum in Tel Aviv, Cohen said that Iran believes Israel is behind the attacks on its nuclear experts, which have killed four scientists since November 2010. "It doesn't matter if it's true or not that Israel took out the nuclear scientists," Cohen said. "A major, serious country like Iran cannot let this go on. They want to deter Israel and extract a price so that decision makers in Israel think twice before they order an attack on an Iranian scientist."

Cohen said Iran was working very hard abroad through the Iranian Revolutionary Guards to hit Israeli targets.

"Over the past year three serious attacks were thwarted that were on the verge of being carried out," the Shin Bet head said. "In Turkey against the general consul in Istanbul; in Baku, Azerbaijan; and two weeks ago in Thailand."

Israel's main dilemma in the coming year, Cohen added, was how to stop Palestinian terror groups in Gaza from obtaining rockets that could reach the metropolitan Tel Aviv area, but without becoming embroiled in a large-scale military action in Gaza.

Cohen said the terror groups' main goal was to increase the range of their missiles to the greater Tel Aviv area, as well as their precision and the size of their warheads.

Cohen said missile experts from abroad were now in Gaza helping Hamas and Islamic Jihad increase the range of the missiles, but conceded that this put Israeli security experts in a difficult place.

Cohen also said that over the past 18 months, Iran has distanced itself from Hamas and invested more in Islamic Jihad in Gaza, because the Iranians "realized that Hamas has political considerations."

The situation in the south has grown worse due to conditions in Sinai, said Cohen. "It's no problem to shoot from Sinai at Israeli planes or ships," he said. "At the moment, Egypt can't take control of the situation because of internal difficulties."

Israel is "in a dilemma over what to do if squads are spotted that are about to attack us from the area of a country with which we have a peace treaty, but has been having difficulty implementing their sovereignty," Cohen said.

During the hour-long lecture, Cohen also discussed the attitude of the security establishment toward Israel's Arab community.

"They are not a fifth column and we don't consider them as such," Cohen noted. "We relate to them as a Palestinian public that identifies with their brethren in Judea and Samaria."

Cohen presented statistics showing that over the past year, there had been only three terror attacks in which Israeli Arabs had been involved, and that Israeli-Arab involvement in terror has declined.

"Their involvement in terror is not great," Cohen said. "We arrested 20 to 30 Arab Israelis last year, as opposed to 2,000 Palestinians from Judea and Samaria. The problems with Arab Israelis are complex, but they are not security problems. They are alienation, integration, employment, poor municipal management, crime and drugs.

"The ideological leadership of the Arab public in Israel," Cohen continued, "is much more extreme than the public, and sometimes pulls in directions with which the public does not identify."

Cohen said another group that feels growing alienation from the state is the faction in the religious public that has lost confidence in its leadership. Cohen said these were a few dozen extremists, mainly from Yitzhar (referring to a West Bank settlement ).

"They have decided to take the road of terror," Cohen said, adding that "because they can't harm the government and the Israel Defense Forces, they lash out at Arabs and [their] sacred symbols. To their mind, the worse it gets, the more the government will have to think before it destroys a shack in a settlement. We treat this as terror."

Cohen said the Shin Bet was trying to deal with Jewish terror "in the best way possible," and noted that the past two months had seen a significant decline in violence by the group.

With regard to the Palestinians, Cohen said Palestinian President Mahmoud Abbas did not want to negotiate with Israel, because Abbas believes the current government will offer no more than what he had received from previous regimes.

"They see what the boundaries of the prime minister's flexibility are and who makes up the coalition, and they know the maximum this government will offer will not reach their minimum," Cohen said. Therefore, he added, the international community was focusing its efforts on preventing escalation between the Israelis and the Palestinians.