A '''fast attack craft''' ('''FAC''') is a small, fast, agile, offensive, often affordable [[warship]] armed with [[anti-ship missile]]s, [[Naval gun|gun]] or [[torpedo]]es. FACs are usually operated in close proximity to land as they lack both the [[seakeeping]] and all-round defensive capabilities to survive in [[Blue-water navy|blue water]]. The size of the vessel also limits the fuel, stores and water supplies. In size they are usually between 50&ndash;800 tonnes and can reach speeds of {{convert|25|&ndash;|50|kn|km/h}}.<ref>{{cite web|url=http://www.amiinter.com/pagex.php?pg=vesseltypes#fast_attack |title=AMI International - Definitions of Vessel Types [ &#93; |publisher=Amiinter.com |access-date=2015-03-11 March 2015}}</ref>

A fast attack craft's main advantage over other warship types is its affordability. Many FACs can be deployed at a relatively low cost, allowing a navy which is at a disadvantage to effectively defend itself against a larger adversary.<ref>{{cite web|url=http://www.taipeitimes.com/News/front/archives/2012/09/09/2003542316 |title=Taiwan must rethink naval strategy: expert |publisher=Taipei Times |date=4 March 2015-03-04 |access-date=2015-03-11 March 2015}}</ref> A small boat, when equipped with the same weapons as its larger counterpart, can pose a serious threat to even the largest of capital ships. Their major disadvantages are poor seagoing qualities, cramped quarters and poor defence against aerial threats.

The idea was revived shortly before World War I with the craft using new gasoline engines. Italy and Great Britain were at the forefront of this design, with the [[Coastal Motor Boat|coastal motor boat]] (CMB) and the ''[[MAS (boat)|motobarca armata silurante]]'' (MAS) (Italian: "torpedo armed motorboat"). The outstanding achievement of the class was the sinking of the Austro-Hungarian battleship {{SMS|Szent István}} by ''MAS. 15'' on June 10, June 1918. The equivalent achievement for the CMBs was a lesser success; during the [[Russian Civil War]] CMBs attacked the Red Fleet at anchor at Kronstadt on June 18, June 1919, sinking the cruiser {{ship|Russian cruiser|Pamiat Azova||2}} for the loss of four craft.

[[File:HMS Ystad R142.JPG|thumb|left|The Swedish ''Ystad''-class missile boat HSwMS ''Ystad'' (R142)]]

With the development of the [[anti-ship missile]], FACs were reborn in the Soviet Union as "[[missile boat]]s" or "missile cutters". The first few missile boats were originally torpedo boats, with the torpedo tubes replaced by missile launchers. Again, small fast craft could attack and destroy a major warship. The idea was first tested by the Soviet Union which, in August 1957, produced the {{sclass2|Komar|missile boat|4}} which mounted two [[P-15 Termit]] missiles on a {{convert|25|m|ft|sing=on}} hull with a top speed of around {{convert|40|kn|lk=in}}. Endurance was limited to {{convert|1000|nmi|lk=in}} at {{convert|12|kn}} and the vessels had supplies for only five days at sea. 110 Komar-class vessels were produced, while over 400 examples were built of the following {{sclass2|Osa| missile boat|4}} with a significant portion of the total being sold to pro-Soviet nations.

The first combat use of missile boats was an attack by two Egyptian Soviet-built Komar-class boats on the Israeli destroyer [[INS Eilat (1955)|''Eilat'']] on 20 October 1967, several months after the [[Six-Day War]]. The two boats launched a total of four P-15 missiles, three of which struck the ''Eilat'' and sank her with the loss of 47 crew dead or missing and over 90 wounded.<ref>{{cite web|author=John Pike |url=http://www.globalsecurity.org/military/world/israel/k40-eilat.htm |title=Eilat Destroyer |publisher=Globalsecurity.org |date=1967-10-21 October 1967 |access-date=2015-03-11 March 2015}}</ref>

The Soviet FACs prompted a [[NATO]] response, which became more intense after the sinking of ''Eilat''. The Germans and French worked together to produce a new FAC, resulting in the ''[[{{sclass|La Combattante class |fast attack craft|La Combattante]]''5}} class, first commissioned in 1968. Built on a {{convert|47|or|49|m|ft|sing=on}} hull with four MM-38 [[Exocet]] missiles, a 76&nbsp;mm gun forward and 40&nbsp;mm twin guns aft, these vessels have a top speed of {{convert|36|kn}}. Built until 1974, a total of 68 Combattante IIs were launched. The design was immediately followed by the [[La Combattante III-class fast attack craft|Combattante III]], and a great many other shipyards produced their own versions of the Combattante, including the Israeli Sa'ar/''Reshef'' variants.

Size has also increased, some designs reaching up to [[corvette]] size, 800 tonnes including a [[helicopter]], giving them extended modes of operation. While the Israeli [[{{sclass2|Sa'ar 4-class |missile boat]]|1}}s, for example, had a 58 metre hull and 415 ton displacement, the [[{{sclass2|Sa'ar 5-class |corvette|Sa'ar 5]]}} is 85 metres in length and displaces 1,065 tons, and is officially rated as a corvette.