Two months after Simchas Torah 5744, the Rebbe came out with a campaign to say Hareini Mekabel before davening and Ach Tzadikim afterward. The Rebbe explicitly stated that he was doing so because of the instability in the world, מלכויות מתגרות זו בזו.
The Rebbe spoke about the increased friction between various nations in recent months and weeks. The way we can better the situation is (not by reading all about the newest developments, but) by adding in tefillah, Torah, and gemilus chassadim.
The Rebbe therefore suggested that no matter your nusach, you should add the passage of Hareini Mekabel before davening and the possuk of Ach Tzaddikim afterward. By doing so, you are askin Hashem to bring unity and peace to Yidden and to the world at large.
יט - כ כסלו תשד"מ:
אידיש: לקו"ש חלק כה עמוד 373. | לה"ק: תורת מנחם | אודיו: יט כסלו תשד"מ - שיחה ה