May one leave the news playing on a radio, phone, or computer, into Shabbos during times of war?
The general rule: Some Poskim rule that there involves no prohibition in leaving the radio on into Shabbos, or having a timer activate it on Shabbos. However the majority of Poskim have prohibited it for various reasons. These include: 1) Listening to business related items which is forbidden; 2) playing music through the radio 3) Benefiting from hearing a Jewish talk show, of which the Jew is desecrating Shabbos; 4) It falls under the category of Melachas which make noise, similar to a flour mill, of which it is initially forbidden to arrange before Shabbos to continue into Shabbos. 5) It is belittling to Shabbos. Practically, the widespread custom is to forbid doing so, as regardless of the Halachic discussion, doing so breaks the Shabbos spirit.
During wartime: In a time of great need, such as in times of natural disasters or war in which case one must hear news directives, one may certainly be lenient to do so, leaving the radio on a low volume. [Accordingly, all those currently living in Israel may leave a radio on a low-volume throughout Shabbos for the sake of being updated with any news that may be relevant for their safety. A number of Shabbos observant radio stations will have a silent broadcast playing throughout Shabbos in which important news events will only feature when necessary. The stations include: Moreshet, Kol Chaiy 102.5 FM, 93 FM , 92.8 FM, and Kol Berama 107.6 FM, 105.7 FM, 104.3 FM, 92.1 FM.]
 See Shearim Hametzuyanim Behalacha 80:39; Piskeiy Teshuvos 252:6
 Mahrshag 2:118; Shulchan Melachim 6:72
 Beis Yitzchak 2:31; Mishpitei Uziel 2:52; Har Tzevi 1:183; Rav SZ”A brought in Shearim Hametzuyanim Behalacha 80:39; Minchas Yitzchak 1:107; Az Nidbaru 3:7; 11:15; Igros Moshe 4:60 regarding the prohibition of having a timer do any Melacha on Shabbos
 Piskeiy Teshuvos 252:6; Regarding leaving the radio on for a sick person in order to calm him down, Chelkas Yaakov 1:61 rules that it is allowed while in 3:98 he retracts that ruling and forbids it.