“When you will wage war in your land against the enemy that attacks you, you shall sound the trumpets and be remembered before G-d, your Lord, and you will be saved from your enemies.”
To our chagrin, this verse is only too real in our time, and, essentially in the last 100 years in which the Jewish people has begun to return to its native land. The Rambam considers this verse a positive commandment at the beginning of the laws of fast days. It is appropriate to quote the full text,
“It is a positive commandment to cry out and to sound the trumpets for any trouble that comes upon the community, as it says, ‘against the enemy that attacks you, you shall sound the trumpets.’ That is to say, any thing which vexes you such as drought, locust, the plague, or any similar nemesis, you should cry out and sound the trumpets. This is from the ways of teshuva: that at the time when misfortune comes, people will pray and sound the trumpets, everyone will know that because of their wrongdoings the evil has occurred… This will cause the misfortune to pass. But, if they will not cry out and rather say that this is “the way of the world” and the misfortune is a freak accident, this is an attitude of cruelty and will cause them to embrace their evil ways. Their misfortunes will increase as it says, “And, if you will go with me in a haphazard way, then I will respond with a haphazardous fury.” Meaning, when I bring misfortune upon you in order that you should do teshuva, if then you will say that is merely an accident, I will increase the fury of your misfortune.”
In Taanit 14a it is stated that one may also sound the shofar instead of a trumpet. The Magen Avraham (beginning of the laws of Taanit, Section 576) questions why we do not sound the shofar at times of trouble. Even if one does not fast, there still is a Scriptural commandment to sound the shofar!?
The Netiv Chaim answers in accordance with the verse in our Parsha that the requirement to sound the shofar is only for war in the land of Israel! The Pri Megadim adds that even in the land of Israel the mitzvah does not apply if it is not under our hegemony. These responses do not reflect our current reality. And, in deed, there are public prayer gatherings at which the shofar is blown.
In any case, prayer is a part of “crying out” and one fulfills by it a positive commandment of the Torah. Therefore, in light of the current security situation in Israel, one should have special concentrate during the recitation of Pirkei Tehilim and the prayer on behalf of Acheinu Beit Yisrael