An Arab Israeli was indicted on Wednesday for contact with an enemy agent after he went to Syria and joined rebels fighting the regime of President Bashar al-Assad, security officials said.
Hikmat Massarwa, from Taibe village in Galilee, was also charged at Lod District Court with undergoing military training and for travelling overseas illegally, the Shin Bet domestic security agency said.
Israel is still technically at war with Syria and it is illegal for its citizens to go there.
In a statement detailing the reasons for the arrest, the Shin Bet said it viewed Arab Israeli participation in the Syrian civil war as "a very dangerous phenomenon."
Massarwa, who was born in 1984, was arrested on March 19 in a joint Shin Bet and police operation after returning from Syria, where he underwent military training with the rebels, the statement said.
"Massarwa went to Syria with the aim of joining world jihad elements who are working against the Syrian army" and had had gone through military training and been instructed on how to use weapons at a rebel camp which he helped set up.
"It was proposed, among other things, that he carry out a suicide attack against the forces of the Assad regime, but he says he refused to do it.
"He was interrogated and asked many questions about Israel and the IDF (Israel Defence Forces) and the sorts of weapons it uses, and also questioned about the (nuclear) reactor in Dimona."
Massarwa also told them he was "asked to carry out a terror attack in Israel" telling them he had refused, the statement said, without giving further details.
Shin Bet "sees Arab Israelis going out to Syria as a very dangerous phenomenon," it said, indicating they were likely to come in contact with militants and activists hostile to Israel.
Israel shares an 80-kilometre (50-mile) frontier with Syria, which cuts across the Golan Heights plateau. Fighting from Syria's two-year civil war occasionally spills over onto the Israeli-controlled sector, which was seized during the 1967 Six Day War.
Israel's defence establishment is closely monitoring the ceasefire line out of concern that jihadist elements among the rebels fighting the Assad regime could attack the Jewish state.