Question: As one isn’t supposed to recite prayers requesting things on Shabbos, should Shuls be reciting the tefilla for the tzahal (IDF)?
Answer: Rambam (Shabbos 30:12) writes that one mustn’t make personal requests on Shabbos. Thus, the Mishna Berura (584:1) writes that we don’t say avinu malkeinu when Yom Kippur falls on Shabbos (except for during neila).
The Shulchan Aruch (OC 288:9) writes that one may pray in emergency situations such as for a choleh (one who’s sick) in critical danger.
The Magen Avraham (OC 288:14) questions the common practice of the gabbai reciting a mi sheberach for cholim who aren’t critically ill. It has, however, become accepted practice to do so, though one should add the words Shabbos he melizok.. The Machtzis Hashekel explains that these words serve to remind us not to be too upset and reassure the choleh that Shabbos itself can aid their recovery. Nonetheless, the Aruch Hashulchan (OC 287:2) writes that if he had the power he’d abolish this mi sheberach on Shabbos (except for those who are critically ill). Elsewhere, (OC 417:9) he questions the practice of saying yehi ratzon on Shabbos Mevorchim (as it is full of requests), again saying that if he’d have the power, he’d annul it. Indeed, the minhag Chabad is not to say it.
Another exception is when such requests are part of the regular tefilla. Thus, the Tur (OC 188) and Mishna Berura (188:9) write that we can say the requests in bentsching. R’ Chaim Berlin (Nishmas Chaim 23) justifies the tefillos for the community (rather than for the individual) that are said as part of the davening.
Many hold that the tefillos composed by the Chief Rabbinate such as the tefillos for the State of Israel and the tzahal fit into this category.
It would seem that even those that do not usually recite the tefillos for Israel on Shabbos (dues to their views on Zionism or based on poskim that we can no longer add to our tefillos) may and should do so now, as Israel and its soldiers are unfortunately in critical danger.