A powerful, but unofficial, force.
Key point: The exact details of Israel’s nuclear arsenal is a tightly-held secret.
Israel has never officially admitted to possessing nuclear weapons.
Originally, Israel’s nuclear forces relied on air-dropped nuclear bombs and Jericho ballistic missiles. For example, when Egyptian and Syrian armies attacked Israel during the 1973 Yom Kippur War, a squadron of eight Israeli F-4 Phantom jets loaded with nuclear bombs was placed on alert by Prime Minister Golda Meir, ready to unleash nuclear bombs on Cairo and Damascus should the Arab armies break through.
Though Israel is the only nuclear-armed state in the Middle East, Tel Aviv is preoccupied by the fear that an adversary might one day attempt a first strike to destroy its nuclear missiles and strike planes on the ground before they can retaliate. Currently, the only hostile states likely to acquire such a capability are Iran or Syria.
Most nuclear powers operate nuclear-powered ballistic missile submarines which can spend months quietly submerged deep underwater and at any moment unleash ocean-spanning ballistic missiles to rain apocalyptic destruction on an adversary’s major centers. Because there’s little chance of finding all of these subs before they fire, they serve as one hell of a disincentive to even think about a first strike.
In the 1990s the United States declined to provide Israel with submarine-launched Tomahawk cruise missiles due to the rules of the Missile Technology Control Regime prohibiting transfer of cruise missile with a range exceeding 300 miles.
Instead, Tel Aviv went ahead and developed their own. In 2000, U.S. Navy radars detected test launches of Israeli SLCMs in the Indian Ocean that struck a target 930 miles away. The weapon is generally believed to be the Popeye Turbo—an adaptation of a subsonic air-launched cruise missile that can allegedly carry a 200-kiloton nuclear warhead. However, the SLCM’s characteristics are veiled in secrecy and some sources suggest a different missile type entirely is used. An Israeli Dolphin submarine may have struck the Syrian port of Latakia with a conventional cruise missile in 2013 due to reports of a shipment of Russian P-800 anti-ship missiles.
Read more at Israel May Have 300 Nuclear Weapons (Including Submarine-Launched Missiles)