There are three approaches to Yom HaZikaron that are found in the charedi community. By far the most common is that which I practiced during my years in the charedi community: obliviousness and indifference. For the vast majority of charedim, Yom HaZikaron just doesn't register for them. They don't know anyone in the IDF, and they don't want to be part of the national community that is mourning those who fell in battle. If they happen to be walking in the streets while the siren sounds, then they may well stand still out of good neighborly relations, but otherwise they don't see any reason why this day should be significant.