In the late 1990s Syria set into motion plans to obtain its first ever nuclear reactor. Damascus would keep its intention to obtain a small nuclear facility a well kept secret, commissioning North Korean assistance for the construction of a reactor in the Deir Ez Zor desert near the Iraqi border. The facility went unnoticed for several years while undergoing construction, and was closely based on the Korean Yongbon nuclear facility. Even within the Syrian military and government few knew of the nuclear project and special precautions were taken to prevent word of the program from being intercepted - including a reliance on sealed letters to deliver any messages relating to the reactor. Special measures were also reportedly taken to avoid detection via satellite, and despite Deir Ez Zor's close proximity to Iraq where the U.S. military was at the time heavily based American intelligence never discovered the reactor. It took Israeli intelligence several years to gain word of the small Syrian nuclear program, reportedly via an official whose laptop was compromised by Israel's Mossad while in London.
Upon learning of the program, the Israeli military immediately began to explore options to neutralise the facility. While Israel long maintained a sizeable nuclear arsenal of its own, the small state sought to retain this as strategic advantage to ensure its survival. Rather than risk the emergence of any form of nuclear parity with one of its greatest regional adversaries, Israel's leadership was adamant that action needed to be taken before Syria's reactor became operational. While it was uncertain if Syria sought a nuclear deterrent aimed to protect it from a U.S. invasion, with the country firmly in Washington's sights following the 2003 invasion of Iraq, or whether it was primarily aimed at gaining nuclear parity with Israel, remain uncertain. There was little doubt however that the reactor was not being built for entirely peaceful purposes.
In September 2007 the Israeli military launched operation Outside the Box, with the Israeli Air Force striking and disabling the reactor beyond repair. Eight Israeli aircraft, four F-15I heavy strike fighters escorted by four F-16 light fighters, delivered nearly 20 tons of ground penetrating explosives which ensured that the program could not be recovered, and Syria would need to begin anew should it seek to develop nuclear arms. According to the Israel military's briefing papers: “Intelligence assessed that the nuclear reactor had been totally disabled, and that the damage done was irreversible." The destruction of the reactor was closely followed by the assassination of Syrian General Muhammad Suleiman by Israeli naval commandos, with the high ranking official reportedly having been responsible for overseeing the nuclear project. This extra precaution ensured that Syria was unlikely to again pursue the development of nuclear arms.
Israeli military papers stated regarding the operation: “The success of the mission has been measured, then and now, by three components laid forth by the chief of the general staff: destruction of the nuclear reactor, prevention of escalation in the region and the strengthening of (Israeli) deterrence.” Israeli sought a precise pre emptive strike, but also saw the importance of avoiding escalation into a larger war with Syria - a heavily armed state with a large missile and chemical weapons arsenal capable of devastating Israeli targets. As Israeli Air Force Maj. General Amos Yadlin, head of military intelligence at the time of the operation, stated: “In 2007, I was very worried that the operation could trigger war with Syria.... Syria could have launched 100 missiles at us the following morning and we would have been in an entirely different situation.” The large U.S. military presence on Syria's Eastern border was likely a key factor which deterred Damascus from retaliating.
Operation Outside the Box remained an open secret for just over ten years, with Israel refusing to claim responsibility for the attack. This changed only on March 21st 2018 when Israeli military announced that it had been responsible for the attack. Photos and footage of the strike were made public, alongside public statements from leading military figures justifying the attack and explaining Israel's rationale behind taking military action. Reasons for abandoning deniability were twofold. The first was that Israel had in the past year conducted numerous incursions into Syrian territory and openly struck Syrian military targets, meaning any taboo on territorial violations were broken several times over and the Jewish state was unlikely to face serious criticism for having undertaken similar actions a decade prior. The second reason was that the successful operation could serve as an effective example of Israel's military strength and willingness to act preemptively against its adversaries, particularly critical considering both recent losses in Syria and growing tensions with Iran - a state which Israeli's leadership often claims is an aspiring nuclear power. Just hours after Israel claimed responsibility for the attack on the Syrian reactor Israeli Prime Minister Benjamin Netanyahu made a thinly veiled threat towards Iran, stating: "The Israeli government, the Israel Defence Forces and the Mossad prevented Syria from developing nuclear capability. They are worthy of full praise for this. Israel's policy was and remains consistent — to prevent our enemies from arming themselves with nuclear weapons." Prime Minister Netanyahu has repeatedly referred to the Iranian state as an imminent threat to Israel's existence, and indicated that Israeli was willing to act to prevent Tehran from acquiring nuclear parity with Tel Aviv. Ultimately whether Israeli will attempt a similar operation against nuclear facilities in Iran, a far more distant and heavily armed power operating state of the art air defences and with fewer compunctions about launching retaliation, remains to be seen, but the risks of such action remain great indeed.