As Iran’s Houthi militia launched a surface-to-surface missile towards the Red Sea town of Eilat Sunday, intercepted by Israel’s Arrow 3 missile defence system, experts ask why Friday’s attack on Tel Aviv went undetected for 2,600 kilometers.

The Sunday attack follows Israel’s first direct hit on Yemen at the weekend targeting Hodeida Port, killing six and wounding around 87 others in retaliation for a drone attack from Yemen on a residential building in Tel Aviv that killed one man and wounded multiple other people.

The attack on Israel’s central city in the early hours of Friday morning has sparked an investigation as to how the Yemeni militia infiltrated Israel’s air defence systems with no alarms sounded to warn residents to go to shelters.

Onn Fennig, CEO of R2, an Israeli anti-drone manufacturer which is training international militaries such as the British armed forces in anti-drone warfare, said: “Nobody in this field thinks it was identified on the day. These systems are extremely hard to detect, for many reasons."

The drone which made the hit in Israel’s second city was able to fly more than 2,600 kilometers, according to the Israeli Air Force, without being detected, meaning air defence systems from allies on its indirect route across the region, including the UK, US and Egypt, also did not detect the breach.

Fanning said: “The IDF said it was identified and misclassified but what does that mean that all our allies misclassified it?”

This specific occasion raises many questions about the Israeli Air Force’s ability to detect such threats. “I think the IDF has a lot of answers to give as does the Ministry of Defence to Israeli citizens,” he said.

This kind of drone is “extremely hard to find," he admitted, speaking to Iran International. “They’re flying very low, below radar mostly, they’re using the terrain to hide from radars and other detection sensors, and in many cases they have low radar signatures, so it’s hard for radars to catch them,” he explained.

Often made out of plastic or carbon composites, they have a low radar signature, legacy radars designed to detect metallic objects. “Once you make these drones out of plastic or composite materials, radars aren’t suitable and so you need other techs to detect it,” he added, the solution a blend of multiple systems working together such as radars, cameras and acoustic centers like Ukraine is using now against Iranian drones in Russia.

Another factor which makes these drones able to evade detection is the smaller numbers. “If there were more, the radars might detect them but one or two, the legacy systems won’t be able to detect it,” he said.

It comes in contrast to the April barrage of Israel when around 350 drones, rockets and missiles were sent by Iran, intercepted by Israel and a US-led coalition.

Drones are flying over Israel three to five times a day as the Jewish state fights Iran’s proxies across its borders, including the north where they are fighting Lebanon’s Hezbollah terror group.

An investigation by the Israeli Air Force announced Sunday that the IAF was at the time of the infiltration already in combat with an Iran-backed drone from Iraq.

The number of spotters has now been doubled as the implications of the threat reverberate as far as Washington.

The IAF said the Iranian made drone took a circuitous route across countries including Eritrea and Sudan, taking 16 hours to reach its target.

It tracked the drone for six minutes while it approached Tel Aviv from the sea, the IAF said Sunday.

“Anyone can make a drone at home for less than $1,000”, Fennig said. “Warfare is changing and the balance between the strong and the weak is changing on its head. It’s not economically viable to shoot down $1,000 quad copter with a $700,000 missile. Those from Yemen and Iran can be more, as much as $30,000, but the imbalance is still there.”

Intelligence analyst, Ronen Solomon, a research consultant for over a decade for Israel’s Ministry of Defence, told Iran International that if there was an error spotting the UAV, it could have been that they had taken parts from a Western, or non-enemy plane, and put it on the UAV.

“For a controller looking at a flight coming from the sea or Egypt to Tel Aviv with western identification, they would hesitate to interrupt it,” he said. “Maybe this is the case when the air force said it was human error and it didn’t think it was a suicide UAV.”

He said that in those early hours of Friday morning when the drone struck an apartment building in central Tel Aviv, there are many long distance flights on the same route as the suicide drone which is believed to have been headed for the US embassy on Israel’s coastline.

“I am now assuming it was traveling through civilian air traffic and maybe flying next to other planes which were also landing at Ben Gurion so if they saw it near an airplane, maybe they would be afraid of doing what happened in Tehran,” Solomon said, referring to the Ukrainian airliner downed by the IRGC killing all 176 people on board.

However, another possibility is that Israel simply did not see the UAV. “If it was flying near a civilian plane, maybe they didn’t see it, and maybe they saw it too late,” he said as the investigation continues.

The Houthis began a Red Sea maritime blockade in November, affecting one of the world’s major trade routes. Multiple seamen have been killed and dozens taken hostage in the siege which began targeting Israeli linked vessels but has expanded to international shipping.

Since Iran’s Supreme Leader gave orders for the blockade in November, “hundreds of ballistic missiles, cruise missiles and drones” have been launched against Israel from the Iran-backed Yemeni militia, with one landing in an area outside Israel’s southern port town of Eilat, according to Israel’s Prime Minister, Benjamin Netanyahu.

The Yemeni port struck on Saturday has been used to smuggle weapons from Iran, Netanyahu said, with the airstrike targeting fuel depots and energy-related sites in a bid to cripple the militia’s economic resources.

However, after a weekend of tit-for-tat strikes, the crisis, sparked by Israel’s war against Iran-backed Hamas in Gaza, is spiralling.

The IRGC’s Sepah Media said Iran’s IRGC has given official approval for retaliatory strikes since the weekend attack with a banner now in Tehran’s Palestine Square warning that Friday’s explosion was only a “test” with a “swarm” of drones headed for Israel’s central city, warning residents to “run now”.

In defiant terms, Israel’s defence minister, Yoav Gallant, said Israel’s response will continue to be firm. “The blood of Israeli citizens has a price. This has been made clear in Lebanon, in Gaza, in Yemen, and in other places - if they will dare to attack us, the result will be identical.”

The fear now is that if a Houthi drone can enter Israeli air space, that it can either crash drones into planes or even the airport, says Solomon.

“The Houthis have attacked ships using air and sea tracking real time applications and what’s worrying now is that if they can fly near a plane, they can attack a plane en route to the airport,” he said.

Netanyahu has been vocal about Iran’s responsibility for the ongoing attacks from Yemen and the Islamic Republic’s proxies in the region.

“The drone attack that struck Israel in the early morning hours yesterday shows that more than defensive action is needed to curtail the Houthis. Offensive action is also needed. It’s needed to ensure that Iran's terror proxies pay a price for their brazen aggression,” he said.

Speaking of the maritime blockade, which has seen a more than 20-nation coalition formed and led by the US, to repel the Houthi attacks, Netanyahu added: “The international community must redouble its efforts to protect this vital waterway and to hold both the Houthis and their Iranian sponsors accountable for their aggression.”

He said Israel is being attacked by Iran and its proxies on seven fronts, the Houthis in Yemen, Hamas in Gaza, Hezbollah in Lebanon, Shiite militias in Iraq and in Syria, Iran backed terror attacks in the West Bank and the direct attack from Iran on April 14.

The inaugural assault saw hundreds of projectiles sent towards Israel, retaliation for an alleged Israeli strike on the Iranian consulate in Damascus. Most of the assault was intercepted by Israel and a US-led coalition.

“In defending ourselves against this Iranian terror axis, Israel stands on the front lines against a regime that threatens the entire Middle East, that threatens the entire world,” added Netanyahu.

“All those who seek to harm us will pay a very heavy price for their aggression,” he warned as the war of words escalates deeper.