 However, as of the 2010 Strategic Defence and Security Review, the Royal Navy loads only eight of the missile tubes with the Trident II submarine-launched ballistic missiles, each armed with up to eight nuclear warheads.In addition to the missile tubes, the submarines are fitted with four 21 inch (533 mm) torpedo tubes and carry the Spearfish heavyweight torpedo, allowing them to engage submerged or surface targets at ranges up to .Two SSE Mark 10 launchers are also fitted, allowing the boats to deploy Type 2066 and Type 2071 decoys, and a UAP Mark 3 electronic support measures (ESM) intercept system is carried.