I simply would not translate it - this is the acronym of the security service. You would not translate KGB, would you? ;-)

GSS significa "General Security Services", como se puede ver en el texto abajo (de la primera referencia):

GSS DEFENDS METHODS AS VITAL TO SECURITY

ISRAEL LINE TUESDAY, MAY 19, 1998

The General Security Services revealed information on Monday indicating that several attempts to kidnap Israeli dignitaries from the political, judicial, academic and media establishments have been foiled during the last year, MA'ARIV reported.
According to the GSS, the intended victims were to be held as hostages
until the release of Palestinian terrorists currently incarcerated in
Israel. GSS sources also said that several suicide bombings were stymied.
These revelations came during a briefing to the High Court of Justice,
which is currently debating the viability of physical interrogation of
terrorist suspects. The GSS told the Court that current methods resulted in
the frustration of the planned terrorist activities. GSS head Ami Ayalon
added that without the use of physical interrogation, Israel's ability to
protect its citizens would be severely compromised.
MA'ARIV also reported that the GSS provided the High Court of Justice with
terrorist statistics, saying that within the past two-and-a-half years, 96
Israelis have been killed and 707 injured as a result of terrorism.

Otros ejemplos y referencias:

THE PALESTINIAN GSS ALSO OPERATES IN THE HEART OF WESTERN ...
... Akarama Sabri, the Mufti of Palestine, was appointed ... receives his salary from the Palestinian Authority, and ... on the Temple Mount, despite protests from Israel. ...
www.mfa.gov.il/mfa/go.asp?MFAH08md0

Outpost, November 1997, p. 3
... Morag junction, on January 1, 1992, and has taken part in the killings of at least ten collaborators with Israel. He currently serves in the Palestinian GSS. ...
www.afsi.org/OUTPOST/97NOV/nov3.htm

News from Israel
... afterwards, "escaped from jail". When it seemed that Israel had forgotten
them, they joined the Police, or the Palestinian GSS. ...
www.isrinfo.demon.co.uk/articl63.htm

Israel's Media Watch Lada'at (IMW) - GSS Agent Avishai Raviv and ...
... Agents. Israel's Media Watch calls for State Comptroller review of GSS-Raviv-Eyal improprieties (in English and Hebrew ) November 1999. ...
www.geocities.com/CapitolHill/2527/listraviv.htm

En español, las dos referencias a continuación:

CALUMNIAS PALESTINAS TEMA
... los Servicios Generales de Seguridad palestinos y confidente de Arafat. El capitán
y la tripulación del buque eran miembros de la Policía Naval palestina. ...
www.israel-embassy.org.ar/calumniaspal.html

RESUMEN DE LA PRENSA HEBREA (OPG) - 11-Oct-94
... fue expulsado del ejercito egipcio o de la brigada palestina Ein Jalut ... Y la red
de los Servicios Generales de Seguridad de los palestinos en Gaza, que debio ...
www.israel-mfa.gov.il/mfa/go.asp?MFAH0bmw0





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Note added at 2003-02-26 20:33:29 (GMT)
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La sigla está en inglés. En el caso de KGB, no hay que traducir, pues serían las iniciales en ruso. En países que hablan español, no se dice GSS, pero \"Servicios Generales de Seguridad de los palestinos\", como indicado arriba.

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Note added at 2003-02-26 20:35:49 (GMT)
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La referencia abajo traduce todo, nombre y sigla:

T-BP-20
... así como en el caso de que la Autoridad Palestina decida declarar ... de Estado Mayor y el jefe de los SGS (Servicios Generales de Seguridad), Arafat disminuyó ...
www.embajada-israel.es/politica/t-bp-20.html