signed (prior to the formation of the Soviet Union) as evidence of violation of international protocol. Shore stations can locate a break in a cable by electrical measurements, such as through spread-spectrum time-domain reflectometry (SSTDR), a type of time-domain reflectometry that can be used in live environments very quickly. Presently, SSTDR can collect a complete data set in 20 ms. Spread spectrum signals are sent down the wire and then the reflected signal is observed. It is then correlated with the copy of the sent signal and algorithms are applied to the shape and timing of the signals to locate the break. A cable repair ship will be sent to the location to drop a marker buoy near the break. Several types of grapples are used depending on the situation. If the sea bed in question is sandy, a grapple with rigid prongs is used to plough under the surface and catch the cable. If the cable is on a rocky sea surface, the grapple is more flexible, with hooks along its length so that it can adjust to the changing surface. In especially deep water, the cable may not be strong enough to lift as a single unit, so a special grapple that cuts the cable soon after it has been hooked is used and only one length of cable is brought to the surface at a time, whereupon a new section is spliced in. The repaired cable is longer than the original, so the excess is deliberately laid in a "U" shape on the seabed. A submersible can be used to repair cables that lie in shallower waters. A number of ports near important cable routes became homes to specialized cable repair ships. Halifax, Nova Scotia, was home to a half dozen such vessels for most of the 20th century including long-lived vessels such as the CS Cyrus West Field, CS Minia and CS Mackay-Bennett. The latter two were contracted to recover victims from the sinking of the RMS Titanic. The crews of these vessels developed many new techniques and devices to repair and improve cable laying, such as the "plough". Intelligence gathering Underwater cables, which cannot be kept under constant surveillance, have tempted intelligence-gathering organizations since the late 19th century. Frequently at the beginning of wars, nations have cut the cables of the other sides to redirect the information flow into cables that were being monitored. The