Iran vows 'strong and complex' attack on Israel: WSJ

Iran is preparing a counterattack on Israel using more powerful warheads and other weaponry, according to a report on Sunday by the Wall Street Journal, which cited Iranian and Arab officials familiar with the plans.

Iran's response is anticipated to go beyond missiles and drones, according to the WSJ, which emphasised that it remains to be seen whether the threats are real or "just tough talk".

Iran's Islamic Revolutionary Guard Corps said on Sunday the country would "certainly" launch a new attack against Israel, a day after its Supreme Leader Ayatollah Ali Khamenei vowed a harsh retaliation.

"Details cannot be discussed, but it will certainly be carried out," Ali Fadavi, the IRGC's deputy commander in chief, was cited as saying by Iran's semi-official Iranian Students' News Agency.

ISNA reported that the potential attack is likely to be named Operation True Promise 3, following previous missile strikes on Israel in April and October.

On Saturday, Khamenei said that Tehran and its regional allies would provide a "crushing response" to both Israel and the United States.

Israel's 26 October attack on Iran, which involved over 100 fighter jets targeting military sites across Iran, killed five people, including one civilian.

Also on Sunday, Israel's military said it had captured a "Syrian spy" for Iran and had thwarted an alleged planned attack by what it described as "Iranian terror networks".

It identified the suspect as Ali Soleiman al-Assi, a Syrian citizen living in the area of the southern village of Saida.

"His activities included gathering intelligence on IDF (Israeli military) troops in the border area for future terror activity of the network," it claimed in a statement.

The military said the operation took place "in recent months", adding that the Syrian citizen "was detained and transferred for interrogation in Israel".

It claimed operation "prevented a future attack and led to the exposure of the operational methods of Iranian terror networks located near the (occupied) Golan Heights".

The Syrian Observatory for Human Rights, a Britain-based war monitor, had previously reported that Israel had seized a Syrian man on 19 July.

"Israeli forces detained a citizen who worked as a driver to transport milk to the capital Damascus," the war monitor said in July.

It added that the Syrian was detained in the village of Al-Razatiya, in a southern province bordering the Golan Heights, which was occupied by Israel in 1967.