Ansar Allah released a photograph on 1 November showing a Zulfiqar launch to illustrate its attacks on Israel. (Ansar Allah)

The Yemeni rebel group Ansar Allah (Houthis) has been launching Zulfiqar ballistic missiles and Quds cruise missiles at Israel, not new types of weapons, according to two letters submitted to the United Nations Security Council (UNSC) by Gilad Erdan,the Israeli ambassador to the UN.

The letters said Zulfiqars were launched from Yemen towards Israel on 31 October, 4 November, 9 November, and 14 November. The one on 4 November has not been previously reported, while the Israeli military announced at the time that the other three were shot down by its Arrow Weapon System, with an Arrow 3 exoatmospheric interceptor used for the first time on 9 November.

Another ballistic missile was intercepted on 6 December, after the letters were submitted to the UNSC.

The letters also said that five Quds land-attack cruise missiles were launched at Israel on 19 October, two on 27 October, several on 31 October, and one more on 22 November.

An artist's portrayal of the Northrop Grumman LGM-35A Sentinel intercontinental ballistic missile. (Northrop Grumman)

The US is undergoing large-scale recapitalisation of its nuclear deterrent capability, with warheads central in this process: five warhead programmes are under way, two of which are in production and in-service phases, and three programmes are in development, according to a Department of Energy (DoE) National Nuclear Security Administration (NNSA) annual report.

The two in production are the B61-12 air-launched gravity bomb, which is replacing four older, in-service B61 variants; and the W88 Alteration (Alt) 370 submarine-launched ballistic missile (SLBM) warhead, which is replacing the W88, the larger-yield warhead fitted to the US Navy's (USN's) Trident D5 SLBM, the NNSA said in its fiscal year (FY) 2024 Stockpile Stewardship and Management Plan (SSMP) report presented to Congress on 27 November.

For B61-12, the first production unit (FPU) was delivered in November 2021, full-scale production (Phase 6.6) commenced in 2022, and (as the SSMP confirmed) the warhead is cleared for operational deployment on the B-2 Spirit strategic bomber.

The Shahed 136 is of great concern for air-defence planners and industry since its debut in Ukraine in 2022. Skyfortress has developed a solution that can detect and track these loud and slow munitions without the use of active systems such as radars or electro-optical sensors. (Sergei Supinsky/AFP via Getty Images)

Representatives from Skyfortress – a Ukrainian non-governmental organisation – have disclosed details of work to develop and install an acoustic sensor network for the detection and tracking of aerial threats.

Speaking at SAE Media Group's Air and Missile Defence conference in London, the representatives said the Skyfortress detection and tracking system combines cheap and domestically designed passive sensors to detect, track, and classify airborne threats. It consists of an array of acoustic sensors that gather information and feed this into Ukraine's national air-defence command-and-control network, known as ‘Virazh'.