(ט) וְכִֽי־תָבֹ֨אוּ מִלְחָמָ֜ה בְּאַרְצְכֶ֗ם עַל־הַצַּר֙ הַצֹּרֵ֣ר אֶתְכֶ֔ם וַהֲרֵעֹתֶ֖ם בַּחֲצֹצְרֹ֑ת וְנִזְכַּרְתֶּ֗ם לִפְנֵי֙ יְהֹוָ֣ה אֱלֹֽהֵיכֶ֔ם וְנוֹשַׁעְתֶּ֖ם מֵאֹיְבֵיכֶֽם׃
(9) When you are at war*When you are at war Meaning of Heb. uncertain. in your land against an aggressor who attacks you, you shall sound short blasts on the trumpets, that you may be remembered before your God יהוה and be delivered from your enemies.

This is a defensive war, What are the theological implications of a defensive war?

(א) כִּֽי־תֵצֵ֨א לַמִּלְחָמָ֜ה עַל־אֹיְבֶ֗ךָ וְֽרָאִ֜יתָ ס֤וּס וָרֶ֙כֶב֙ עַ֚ם רַ֣ב מִמְּךָ֔ לֹ֥א תִירָ֖א מֵהֶ֑ם כִּֽי־יְהֹוָ֤ה אֱלֹהֶ֙יךָ֙ עִמָּ֔ךְ הַמַּֽעַלְךָ֖ מֵאֶ֥רֶץ מִצְרָֽיִם׃ (ב) וְהָיָ֕ה כְּקָֽרׇבְכֶ֖ם אֶל־הַמִּלְחָמָ֑ה וְנִגַּ֥שׁ הַכֹּהֵ֖ן וְדִבֶּ֥ר אֶל־הָעָֽם׃ (ג) וְאָמַ֤ר אֲלֵהֶם֙ שְׁמַ֣ע יִשְׂרָאֵ֔ל אַתֶּ֨ם קְרֵבִ֥ים הַיּ֛וֹם לַמִּלְחָמָ֖ה עַל־אֹיְבֵיכֶ֑ם אַל־יֵרַ֣ךְ לְבַבְכֶ֗ם אַל־תִּֽירְא֧וּ וְאַֽל־תַּחְפְּז֛וּ וְאַל־תַּֽעַרְצ֖וּ מִפְּנֵיהֶֽם׃ (ד) כִּ֚י יְהֹוָ֣ה אֱלֹֽהֵיכֶ֔ם הַהֹלֵ֖ךְ עִמָּכֶ֑ם לְהִלָּחֵ֥ם לָכֶ֛ם עִם־אֹיְבֵיכֶ֖ם לְהוֹשִׁ֥יעַ אֶתְכֶֽם׃ (ה) וְדִבְּר֣וּ הַשֹּֽׁטְרִים֮ אֶל־הָעָ֣ם לֵאמֹר֒ מִֽי־הָאִ֞ישׁ אֲשֶׁ֨ר בָּנָ֤ה בַֽיִת־חָדָשׁ֙ וְלֹ֣א חֲנָכ֔וֹ יֵלֵ֖ךְ וְיָשֹׁ֣ב לְבֵית֑וֹ פֶּן־יָמוּת֙ בַּמִּלְחָמָ֔ה וְאִ֥ישׁ אַחֵ֖ר יַחְנְכֶֽנּוּ׃
(1) When you [an Israelite warrior] take the field against your enemies, and see horses and chariots—forces larger than yours—have no fear of them, for your God יהוה, who brought you from the land of Egypt, is with you. (2) Before you join battle, the priest shall come forward and address the troops. (3) He shall say to them, “Hear, O Israel! You are about to join battle with your enemy. Let not your courage falter. Do not be in fear, or in panic, or in dread of them. (4) For it is your God יהוה who marches with you to do battle for you against your enemy, to bring you victory.” (5) Then the officials shall address the troops, as follows: “Is there anyone who has built a new house but has not dedicated it? Let him go back to his home, lest he die in battle and another dedicate it.
מַתְנִי׳ ״וְיָסְפוּ הַשֹּׁטְרִים לְדַבֵּר אֶל הָעָם וְגוֹ׳״, רַבִּי עֲקִיבָא אוֹמֵר: ״הַיָּרֵא וְרַךְ הַלֵּבָב״ — כְּמַשְׁמָעוֹ, שֶׁאֵינוֹ יָכוֹל לַעֲמוֹד בְּקִשְׁרֵי הַמִּלְחָמָה וְלִרְאוֹת חֶרֶב שְׁלוּפָה. רַבִּי יוֹסֵי הַגְּלִילִי אוֹמֵר: ״הַיָּרֵא וְרַךְ הַלֵּבָב״ — זֶהוּ הַמִּתְיָירֵא מִן הָעֲבֵירוֹת שֶׁבְּיָדוֹ, לְפִיכָךְ תָּלְתָה לוֹ הַתּוֹרָה אֶת כׇּל אֵלּוּ, שֶׁיַּחְזוֹר בִּגְלָלָן.
MISHNA: The mishna continues its discussion of the speech given before battle. “And the officers shall speak further to the people, and they shall say: What man is there that is fearful and fainthearted? Let him go and return unto his house” (Deuteronomy 20:8). Rabbi Akiva says: “That is fearful and fainthearted” is to be understood as it indicates, that the man is unable to stand in the battle ranks and to see a drawn sword because it will terrify him. Rabbi Yosei HaGelili says: “That is fearful and fainthearted”; this is one who is afraid because of the sins that he has; he, too, returns. Therefore, the Torah provided him with all these additional reasons for exemption from the army so he can ascribe his leaving to one of them. In this way, the sinner may leave the ranks without having to publicly acknowledge that he is a sinner.

(ז) בַּמֶּה דְבָרִים אֲמוּרִים, בְּמִלְחֶמֶת הָרְשׁוּת. אֲבָל בְּמִלְחֶמֶת מִצְוָה, הַכֹּל יוֹצְאִין, אֲפִלּוּ חָתָן מֵחֶדְרוֹ וְכַלָּה מֵחֻפָּתָהּ. אָמַר רַבִּי יְהוּדָה, בַּמֶּה דְבָרִים אֲמוּרִים, בְּמִלְחֶמֶת מִצְוָה. אֲבָל בְּמִלְחֶמֶת חוֹבָה, הַכֹּל יוֹצְאִין, אֲפִלּוּ חָתָן מֵחֶדְרוֹ וְכַלָּה מֵחֻפָּתָהּ:

(7) The mishna adds: In what case are all of these statements, with regard to the various exemptions from war, said? They are said with regard to elective wars. But in wars whose mandate is a mitzva, everyone goes, even a groom from his room and a bride from her wedding canopy. Rabbi Yehuda said: In what case are all of these statements, with regard to the various exemptions from war, said? They are said with regard to wars whose mandate is a mitzva. But in obligatory wars, everyone goes, even a groom from his room and a bride from her wedding canopy.

Can there be a modern obligatory war - as opposed to an elective war or a defensive war?

(ט) וְהָיָ֛ה כְּכַלֹּ֥ת הַשֹּׁטְרִ֖ים לְדַבֵּ֣ר אֶל־הָעָ֑ם וּפָ֥קְד֛וּ שָׂרֵ֥י צְבָא֖וֹת בְּרֹ֥אשׁ הָעָֽם׃ {ס} (י) כִּֽי־תִקְרַ֣ב אֶל־עִ֔יר לְהִלָּחֵ֖ם עָלֶ֑יהָ וְקָרָ֥אתָ אֵלֶ֖יהָ לְשָׁלֽוֹם׃
(9) When the officials have finished addressing the troops, army commanders shall assume command of the troops. (10) When you approach a town to attack it, you shall offer it terms of peace.*offer it terms of peace Or “call on it to surrender.”

(ה) שְׁלֹשָׁה כְּתָבִים שָׁלַח יְהוֹשֻׁעַ עַד שֶׁלֹּא נִכְנַס לָאָרֶץ. הָרִאשׁוֹן שָׁלַח לָהֶם מִי שֶׁרוֹצֶה לִבְרֹחַ יִבְרַח. וְחָזַר וְשָׁלַח מִי שֶׁרוֹצֶה לְהַשְׁלִים יַשְׁלִים. וְחָזַר וְשָׁלַח מִי שֶׁרוֹצֶה לַעֲשׂוֹת מִלְחָמָה יַעֲשֶׂה.

(5) Joshua sent three letters to the Canaanites before entering the promised land: At first, he sent them: 'Whoever desires to flee, should flee.'
Afterwards, he sent a second message: 'Whoever desires to accept a peaceful settlement, should make peace.'
Then, he sent again: 'Whoever desires war, should do battle.'

Does our tradition reflect good wartime theory or a reflection of Jewish values? or both?

(א) כי תקרב אל עיר. במלחמת הרשות הכתוב מדבר.

(ב) אל עיר. ולא לכרך.

(ג) אל עיר. ולא לכפר.

(ד) להלחם עליה. ולא להרעיבה ולא להצמאיה (אולי "להצמיאה") ולא להמיתה במיתת תחלואים.

(ה) וקראת אליה לשלום. גדול השלום, שאפילו (מתים צריכים שלום, גדול השלום שאפילו) במלחמה צריכים שלום. גדול השלום, שאפילו [מתים צריכים שלום. גדול השלום,] שדרי רום צריכים שלום, שנאמר (איוב כד) עושה שלום במרומיו. גדול השלום, שחותמים ברכת כהנים בשלום. ואף משה היה אוהב שלום, שנאמר ואשלח מלאכים ממדבר קדמות, דברי שלום.

(1) (Devarim 20:10) "If you draw near to a city": Scripture here speaks of an optional war.

(2) "to a city": and not to a metropolis;

(3) "to a city": and not to a village.

(4) "to do battle with it": and not to reduce it by hunger, thirst, or plague.

(5) "then you shall call out to it for peace": Great is peace, for even in war peace is needed.

(יז) זָכ֕וֹר אֵ֛ת אֲשֶׁר־עָשָׂ֥ה לְךָ֖ עֲמָלֵ֑ק בַּדֶּ֖רֶךְ בְּצֵאתְכֶ֥ם מִמִּצְרָֽיִם׃ (יח) אֲשֶׁ֨ר קָֽרְךָ֜ בַּדֶּ֗רֶךְ וַיְזַנֵּ֤ב בְּךָ֙ כׇּל־הַנֶּחֱשָׁלִ֣ים אַֽחֲרֶ֔יךָ וְאַתָּ֖ה עָיֵ֣ף וְיָגֵ֑עַ וְלֹ֥א יָרֵ֖א אֱלֹהִֽים׃ (יט) וְהָיָ֡ה בְּהָנִ֣יחַ יְהֹוָ֣ה אֱלֹהֶ֣יךָ ׀ לְ֠ךָ֠ מִכׇּל־אֹ֨יְבֶ֜יךָ מִסָּבִ֗יב בָּאָ֙רֶץ֙ אֲשֶׁ֣ר יְהֹוָה־אֱ֠לֹהֶ֠יךָ נֹתֵ֨ן לְךָ֤ נַחֲלָה֙ לְרִשְׁתָּ֔הּ תִּמְחֶה֙ אֶת־זֵ֣כֶר עֲמָלֵ֔ק מִתַּ֖חַת הַשָּׁמָ֑יִם לֹ֖א תִּשְׁכָּֽח׃ {פ}
(17) Remember what Amalek did to you on your journey, after you left Egypt— (18) how, undeterred by fear of God, he surprised you on the march, when you were famished and weary, and cut down all the stragglers in your rear. (19) Therefore, when your God יהוה grants you safety from all your enemies around you, in the land that your God יהוה is giving you as a hereditary portion, you shall blot out the memory of Amalek from under heaven. Do not forget!

To blot out the name of Amalek might require the utter elimination of that tribe. Is this theologically necessary? Is it hyperbole?

(ד) צָרוֹר אֶת הַמִּדְיָנִים, לָמָּה (במדבר כה, יח): כִּי צֹרְרִים הֵם לָכֶם, מִכָּן אָמְרוּ חֲכָמִים בָּא לְהָרְגֶּךָ הַשְׁכֵּם לְהָרְגוֹ.

(4) 4 (Numb. 25:17) “Harass the Midianites”: Why? (As in Numb. 25:18,) “Because they are harassing you.” Hence the sages have said, “If someone comes to kill you, act first to kill him.”7Ber. 62b; Sanh. 72a.

(יג) כָּל הַיָּכוֹל לְהַצִּיל בְּאֵיבָר מֵאֵיבָרָיו וְלֹא טָרַח בְּכָךְ אֶלָּא הִצִּיל בְּנַפְשׁוֹ שֶׁל רוֹדֵף וַהֲרָגוֹ הֲרֵי זֶה שׁוֹפֵךְ דָּמִים וְחַיָּב מִיתָה אֲבָל אֵין בֵּית דִּין מְמִיתִין אוֹתוֹ:

(13) When a person could prevent a murder or a rape by maiming the rodef's limbs, but did not take the trouble and instead saved the victim by killing the rodef, he is regarded as one who shed blood and is liable for death. Nevertheless, he should not be executed by the court.

תַּנְיָא נָמֵי הָכִי נׇכְרִים שֶׁצָּרוּ וְכוּ׳. בַּמֶּה דְּבָרִים אֲמוּרִים, כְּשֶׁבָּאוּ עַל עִסְקֵי מָמוֹן, אֲבָל בָּאוּ עַל עִסְקֵי נְפָשׁוֹת — יוֹצְאִין עֲלֵיהֶן בִּכְלֵי זֵיינָן, וּמְחַלְּלִין עֲלֵיהֶן אֶת הַשַּׁבָּת. וּבָעִיר הַסְּמוּכָה לַסְּפָר, אֲפִילּוּ לֹא בָּאוּ עַל עִסְקֵי נְפָשׁוֹת אֶלָּא עַל עִסְקֵי תֶּבֶן וָקַשׁ — יוֹצְאִין עֲלֵיהֶן בִּכְלֵי זֵיינָן, וּמְחַלְּלִין עֲלֵיהֶן אֶת הַשַּׁבָּת. אָמַר רַב יוֹסֵף בַּר מִנְיוֹמֵי אָמַר רַב נַחְמָן: וּבָבֶל, כָּעִיר הַסְּמוּכָה לַסְּפָר דָּמְיָא. וְתַרְגּוּמָא: נְהַרְדְּעָא.
That was also taught in a baraita, with a caveat: With regard to gentiles who besieged, etc. In what case is this said? It is said in a case where the gentiles came and besieged the town with regard to monetary matters, i.e., banditry. However, if they came with regard to lives, i.e., there is concern that the gentiles will attack, they may go out against them with their weapons, and they may desecrate Shabbat due to them. And with regard to a town that is located near the border, even if the gentiles did not come with regard to lives, but rather with regard to matters of hay and straw, i.e., to raid and spoil the town, they may go out against them with their weapons, and they may desecrate Shabbat due to them, as the border must be carefully guarded, in order to prevent enemies from gaining a foothold there. Rav Yosef bar Manyumi said that Rav Naḥman said: And Babylonia is considered like a town located near the border, and war may be waged there on Shabbat even if the gentiles came for financial gain. And this means the city of Neharde’a, which was located near the border.
(יא) אֲשֶׁר֩ נָתַ֨ן הַמֶּ֜לֶךְ לַיְּהוּדִ֣ים ׀ אֲשֶׁ֣ר בְּכׇל־עִיר־וָעִ֗יר לְהִקָּהֵל֮ וְלַעֲמֹ֣ד עַל־נַפְשָׁם֒ לְהַשְׁמִיד֩ וְלַהֲרֹ֨ג*(במגילות אשכנז לַהֲרֹ֨ג) וּלְאַבֵּ֜ד אֶת־כׇּל־חֵ֨יל עַ֧ם וּמְדִינָ֛ה הַצָּרִ֥ים אֹתָ֖ם טַ֣ף וְנָשִׁ֑ים וּשְׁלָלָ֖ם לָבֽוֹז׃
(11) to this effect: The king has permitted the Jews of every city to assemble and fight for their lives; if any people or province attacks them, they may destroy, massacre, and exterminate its armed force together with women and children, and plunder their possessions—

Ruach Tzahal:

(1) Human Life

The IDF serviceman will, above all, preserve human life, in the recognition of its supreme value and will place himself or others at risk solely to the extent required to carry out his mission.

The sanctity of life in the eyes of the IDF servicemen will find expression in all of their actions, in deliberate and meticulous planning, in safe and intelligent training and in proper execution of their mission. In evaluating the risk to self and others, they will use the appropriate standards and will exercise constant care to limit injury to life to the extent required to accomplish the mission.

(2) Purity of Arms

The IDF serviceman will use force of arms only for the purpose of subduing the enemy to the necessary extent and will limit his use of force so as to prevent unnecessary harm to human life and limb, dignity and property.

The IDF servicemen's purity of arms is their self-control in use of armed force. They will use their arms only for the purpose of achieving their mission, without inflicting unnecessary injury to human life or limb; dignity or property, of both soldiers and civilians, with special consideration for the defenseless, whether in wartime, or during routine security operations, or in the absence of combat, or times of peace.

(3) Personal Example

The IDF serviceman will comport himself as is required of him and will, himself, act as he demands of others, thoughtfully and dedicatedly, aware of his ability and responsibility to serve as a role model to those around him.

The personal example of the IDF servicemen is their acting as is demanded of them and as they themselves demand of others, their clear and convincing readiness to serve as an example to those around them, in their actions and comportment, to create, uphold and foster mutual identification and joint responsibility in properly carrying out their tasks and accomplishing their missions in all areas of military activity.