you are an knowledge graph expert. here are some Temporal Knowledge Graphs tetrad，whose instructure is: subject， predicate， object， time。please read all the tetrads and answer the question.
my tetrads are:
 "Insurgency_(Al-Shabaab)","Use_unconventional_violence","Muslim_(United_Kingdom)","2015-06-20"
 "Muslim_(United_Kingdom)","Use_conventional_military_force","Insurgency_(Al-Shabaab)","2015-06-20"
 "Citizen_(United_Kingdom)","Use_unconventional_violence","Al-Shabaab", "2015-11-28"
 "Combatant_(Al-Shabaab)","Use_unconventional_violence","Al-Shabaab","2009-03-15"
 "Combatant_(Al-Shabaab)","Use_unconventional_violence","Al-Shabaab","2010-04-06"

my question is:
When did the al-Shabaab insurgency use unconventional violence against Muslims in the United Kingdom?

please give me the answer, the answer must be one of the entities in the supplied tetrad. Respond with more than 250 words.
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