Hacked websites in Israel, a reported cyberattack in Iran and a Twitter war between their leaders: the arch foes' animosity is flaring up online.

 

The latest volleys in Israel and Iran's longstanding rivalry coincide with the 20th anniversary of the Israeli army's withdrawal from southern Lebanon, forced out by Iranian-backed Lebanese group Hizbullah.

 

They also come before Jerusalem Day on Friday, an event that typically sees increased tensions.

 

While Israelis celebrate their 1967 capture of the eastern part of the holy city, Iran commemorates the day with events marking the Palestinian and Muslim connection to the holy city and expounds its opposition to Zionism -- the founding ideology of Israel.

 

"We will support and assist any nation or any group anywhere who opposes and fights the Zionist regime," Iran's supreme leader Ayatollah Ali Khamenei tweeted Wednesday.

 

He called for the "defense" of Palestinians and for "thugs like (Israeli Prime Minister Benjamin) Netanyahu" to be overthrown.

 

"The nature of the Zionist regime is incompatible with peace, because the Zionists seek to expand their territories," he added.

 

The lead-up to Jerusalem Day also saw a poster go up on Khamenei's website with a tagline under "Palestine will be Free" reading, "The final solution: Resistance until referendum".

 

Israeli Prime Minister Netanyahu blasted Khamenei in a response on Twitter on Wednesday night.

 

"He should know that any regime that threatens Israel with extermination will find itself in similar danger," Netanyahu wrote on his official account in Hebrew.

 

U.S. Secretary of State Mike Pompeo, who visited Jerusalem last week to discuss Iran with Israeli leaders, weighed in, condemning Khamenei's "disgusting and hateful anti-Semitic remarks."

 

The morning after the Twitter barbs, Israelis woke to a series of cyber attacks targeting websites of businesses, municipalities and NGOs with a message in Hebrew and English: "the countdown to the destruction of Israel began long ago."

 

An accompanying link led to a video showing Israeli commercial capital Tel Aviv in flames, with the words "be ready for a big surprise."

 

There were no immediate details on the group that claimed the attack, naming itself in English "Hackers of Saviour".

 

- Cyber-terrain -

 

Earlier this week, The Washington Post reported Israel had launched a cyber attack against the Iranian port of Shahid Rajaee, located on the Strait of Hormuz, a vital route for international oil traffic.

 

This attack was thought to be in retaliation for a cyber attack against civil hydraulic installations in Israel.

 

Israeli authorities have not confirmed either attack, but allowed doubt to linger through indirect and sometimes metaphorical language.

 

"The Iranian octopus is sending its tentacles to grab us from every direction," outgoing Defense Minister Naftali Bennett said this week.

 

"We must increase the diplomatic, economic, military and technological pressure, and act in other dimensions as well."

 

The next day, army chief Aviv Kohavi said: "We are preparing varied means and unique combat techniques to mortally harm the enemy."

 

The attacks, if confirmed, add a cyber dimension to a series of Israeli air strikes targeting Iranian interests in Syria.

 

Tehran supports Syrian President Bashar al-Assad's regime and has backed it militarily.

 

Israel has launched hundreds of strikes in Syria since the start of the civil war in 2011, targeting Syrian government troops as well as allied Iranian forces and Hizbullah fighters and arms shipments.

 

On Thursday, the Israeli army said it had detected a desire among Iranian forces to withdraw somewhat from the front lines in Syria, putting it down in part to the coronavirus pandemic and economic crisis in Iran.

 

"The main thing we see on the ground is a general vector of withdrawal... not massive, but a general posture of withdrawal," the army said.

 

But, it added, "the Iranians are definitely trying different additional ways to engage with Israel."