Commercial satellite imagery obtained by International Panel on Fissile Material (IPFM) shows significant new construction at the Dimona site in Israel, officially known as the Negev Nuclear Research Centre. IPFM said on 18 February. The imagery was acquired by the SuperView-1 (SV-1) satellite on 4 January. The construction site is located in the immediate vicinity of the buildings that house the nuclear reactor and the reprocessing plant (to the south-west from the buildings.

The exact date the construction began is uncertain, said IPFM. The last satellite image available from Google Earth, which was obtained in September 2011, does not show any activity at the site. The first signs of construction are visible on an image available from the HERE WeGo service (the date of that image is unknown).

“The 2021 image shows that the construction has expanded and appears to be actively underway with multiple construction vehicles present,” said IPFM. “At this stage, the construction appears to be centred around a large-scale excavation area with the size of about 140 metres by 50 metres. The purpose of this construction is unknown.

Israel is a nuclear weapon state outside of the Nuclear Non-proliferation Treaty. As of the beginning of 2019, its nuclear arsenal was estimated to include about 80 warheads. IPFM noted. The non-profit organisation Federation of American Scientists estimates that Israel currently has at least 90 nuclear warheads.

Israel is believed to still be operating the now 50-year-old Dimona plutonium production heavy water reactor, built for it by France. The reactor may be operated now primarily for tritium production. As of the beginning of 2019, Israel may have a stockpile of about 960 ± 130 kg of plutonium, IPFM said.

Israel may also own about 300 kg of HEU that was diverted from the NUMEC plant in the United States in the 1960s. Israel neither admits nor denies being in possession of a nuclear arsenal.

Pavel Podvig, a researcher with the programme on science and global security at Princeton University in New Jersey, told The Guardian that the construction had allegedly begun two years ago.

"It appears that the construction started quite early in 2019, or late 2018, so it's been under way for about two years, but that's all we can say at this point", he noted. In the late 2000s, Israel reportedly used the Dimona site to create replicas of Iran's uranium enrichment centrifuges to test so-called Stuxnet malware in a bid to sabotage the uranium enrichment-related work at the Islamic Republic's Natanz nuclear facility.