Live updates: Follow the latest on Israel-Gaza
Israel’s air strike on Hodeidah, Yemen, on Saturday followed a successful Houthi drone attack on Tel Aviv last week, raising the prospect of the two foes now being locked in a tit-for-tat struggle despite the vast distance between them.
Friday's Houthi attack was the longest range strike in the conflict so far, using a new drone the Houthis have named Yafa, which according to an Israeli assessment on Sunday, travelled 2,600 kilometres to its target on an indirect approach.
Such an extremely long range strike is likely the furthest the group can launch an attack, with the militia previously firing a ballistic missile at Israel with a range of around 2,000km. Most of the group's weapons are based on Iranian designs or entirely Iranian in origin, renamed in Houthi service.
Israel responded to the Tel Aviv strike with one of its longest aerial missions to date, a 3,600km round trip with an unknown amount of time spent over Hodeidah.
Long range strikes
The Israeli air force published images on Sunday of F-15I fighter jets preparing for the mission, showing the jets fitted with fuel tanks which attach to the body of the aircraft for improved aerodynamic performance compared to traditional extra fuel tanks carried under the wing.
The tanks added 4,600 litres of fuel to the jet’s 7,500 litre internal capacity.
At least one of the jets is also pictured with an under-wing fuel tank, meaning the Israelis were pushing the range of their F-15s to the limit. The jets have a roughly 5,000 kilometre “ferry range” – the combinedjourney going out and returning – with additional fuel tanks and no armament.
While the ferry range is comfortably within the roughly 3,600 kilometre round trip to Hodeidah, aerial refuelling would have been needed because once armed with a heavy bomb load, the F-15’s fighting range, or “combat radius,” can be massively reduced.
These ranges made the mission longer than the Israeli strike on Iran, which destroyed an air defence radar on April 19, with Israeli weapons launched after a flight of at least 1,000 kilometres, close to the Iraq-Iran border.
Israeli jets are widely thought to have fired an aero-ballistic missile – a powerful missile launched at speed from high altitude – to reach a target deep inside Iran, counting on the weapon’s range and speed to minimise risk to the Israeli aircraft.
Israel's jets on Saturday would not have faced a similar air defence threat from the Houthis' weakened anti-aircraft arsenal, but would likely have been limited by a very small window to strike before fuel ran low.
The F-15 in the past has proven an extremely high endurance jet, with two F-15s clocking up a 15 hour mission over Afghanistan in 2001, refuelling 12 times during the operation.
While that is an extreme example, the Israelis have a history of long range bombing missions, striking the headquarters of the Palestine Liberation Organisation in Tunis in 1985, a roughly 4,500 kilometre round trip over a six hour mission.
Seventy people in Tunis were killed in the bombing, with Israel claiming the majority were PLO members.
Houthi counter strikes
Saturday’s attack opens the door to further Houthi attacks against Israel, in addition to a ballistic missile attack on Sunday that was intercepted.
One of the longest-range weapons the Houthis possess is the Tufan ballistic missile, which according to Ralph Savelsberg, an professor at the Netherlands Defence University, is a copy of the Iranian Ghadr-F with some possible modifications and a likely range of almost 2,000 kilometres.
Ballistic missiles fly at extremely high altitudes, often beyond the Karman line that separates the Earth’s atmosphere and space.
In November, experts said an Israeli interception of the Tufan using the Arrow 3 missile defence system was the first military engagement in space.
The Houthis also have extensive use of Iran-designed drones, with the longest range being a Samad-3, which by some estimates could hit Tel Aviv with its 1,800 kilometre range.
Despite flying slowly and low under radar, which can make them difficult to detect until they are very close to a target, drones like the Samad are increasingly vulnerable to jet fighters and modern radar systems, especially on air defence systems like Israel’s Iron Dome.
But they don’t pack much of a punch in terms of explosive power and are mainly effective against fragile infrastructure such as power plants and fuel storage.
Lastly, the Houthis have access to cruise missiles, including the Quds-3 which penetrated Israeli airspace for the first time in March, although it appeared to miss its target and land in an open field.
Unlike very long range drones, these missiles have large warheads and could be devastating if they reach their target, but they are expensive compared to attack drones.
