NHEJ employs three strategies for resolving damage, red line and starbursts, at ends. After assembly of core factors and alignment of broken ends, the core complex can (A) attempt to tolerate the break by direct ligation, or rearrange the complex and recruit (B) end-cleaning enzymes for short patch excision, or (C) end-remodeling enzymes for more extensive damage processing. Newly synthesized and incoming nucleotides are shown, blue. (D) NHEJ may employ these strategies hierarchically. The choice and transition from one strategy to the next is likely determined by the complexity of damage at the ends. The NHEJ core complex is shown as described in Figure 2D.