Cruise missiles are among the hardest weapons to stop. But the Israelis are doing it.According to Popular Science, unlike ballistic missiles, which arc up into space before traveling back down towards earth, cruise missiles fly close to the ground, making it hard for radar on the ground that’s pointed up at space to see them.The perceived threat from new cruise missiles is driven by tech developments occurring across the globe, as new materials, better aerodynamics and sophisticated sensors and guidance systems make possible the fielding of weapons, such as hypersonic missiles.Weapons like that were just theoretical only decades ago. Part of any missile defence system depends on sensors, such as specially focused radar, that can detect incoming attacks and then track those weapons as they travel. These radars then send that tracking information to interceptors, which are missiles launched to fly and destroy the incoming attacking missile.Missile on missile is a hard problem because an incoming threat arrives at great speed and because the cost calculus can favour an attacker.Interceptors, such as shorter-ranged US Patriot missile system, are often more expensive than the missiles they are intercepting.And unlike interceptors, which have to hit precisely to work, missiles launched in attack can deploy decoys or countermeasures to redirect interceptors away.So how about Lockheed-Martin built F-35 Lightning fighter jets?Last week, the Israel Defence Forces (IDF) said it used F-35I Adir fighter jets to shoot down a cruise missile, the first known cruise missile intercept by the American-made stealth fighter.“In recent days, a cruise missile launched from the southeast toward Israeli airspace was detected by the IAF’s control and detection systems. After tracking the cruise missile’s trajectory, Adir fighter jets were scrambled and successfully intercepted the missile,” the IDF said, while releasing video of the incident.The report, carried by Breaking Defense and The Drive, said the cruise missile was likely launched from the Iran-backed Houthis in Yemen.No details have so far been provided by the IDF about the exact time and location.However, the claim the missile was “launched from the southeast” toward Israel points with near certainty to the reality that it was launched by Houthi militants.It has also been noted the cruise missile in question looks very similar to the Quds series of weapons used by the Houthis.While the Israelis did not specify what weapon was used to intercept the incoming cruise missile, Israel’s F-35I variants are armed with both the AIM-9X Sidewinder and Aim-120 AMRAAM missiles.The latter is an American beyond-visual-range air-to-air missile capable of all-weather day-and-night operations. It uses active transmit-receive radar guidance instead of semi-active receive-only radar guidance. It is what is called a fire-and-forget weapon, unlike the previous generation Sparrow missiles which required full guidance from the firing aircraft.The cost of one AMRAAM? About US$1.37 million. And that does not include other costs, such as aircraft acquisition, maintenance, training and basic running costs.AIM-9x Sidewinders are much cheaper, all things considered — about US$430,818 for US Navy use and about US$472,000 for USAF use.Israel’s F-35s were declared operational in 2017 and they were used in combat in 2018 for the first time. Israel signed a deal to buy an additional 25 of the aircraft in July.The country will eventually have 75 of the fifth-generation aircraft, Breaking Defense reported. Adir is the Israeli Air Force name for the F-35I, roughly translated as “Mighty” or “Mighty one.”Overall, Israel has taken a unique approach to operating its F-35Is, continuing its tradition of adapting US-provided military aircraft to its exacting specifications.The F-35 is well-equipped to deal with cruise missiles and drones, thanks to its extensive sensor suite including a highly advanced active electronically scanned array (AESA) radar, Electro-Optical Targeting System (EOTS), and sensor-fusion capabilities.Modern AESAs far exceed the abilities of traditional mechanically scanned array radars when ‘looking down’ for hard-to-detect targets and tracking and engaging them once detected.The IDF also holds the title of the first known kill by an F-35, when in March 2021 it shot down two drones it says were launched from Iran.Since the October 7 assault by Hamas that killed more than 1,400 people in Israel, the airborne threat from Yemen has been increasing.On October 18, the Houthis in Yemen launched drones and cruise missiles toward Israel, with the Pentagon saying the USS Carney intercepted 15 drones and four cruise missiles over nine hours, Breaking Defense reported.Another attack was launched on October 27, but the projectiles landed in Egypt. And on October 31 Israel used its Arrow system, which was jointly developed with the US, to intercept a ballistic missile from Yemen.Worst case scenario … with the Houthis effectively having declared war on Israel, more intercepts of their weapons are bound to happen.And if Hezbollah also enters the fray on a larger scale, the Israeli fighter force will be taxed heavily with defending against attacks from north and south by both cruise missiles and drones.