es ▁can ▁grant ▁special ▁bon uses , ▁like ▁faster ▁research ▁times ▁for ▁certain ▁techn ologies ▁or ▁extra ▁fact ories . ▁While ▁some ▁bon uses ▁( like ▁extra ▁fact ories ) ▁are ▁very ▁tang ible , ▁others ▁( like ▁improvements ▁to ▁mor ale ) ▁are ▁more ▁abstract . ▁These ▁abstract ▁bon uses ▁are ▁represented ▁by ▁" n ational ▁spirits " ▁that ▁can ▁be ▁temporary ▁or ▁permanent . ▁Not ▁all ▁national ▁spirits ▁are ▁granted ▁by ▁focus es , ▁and ▁not ▁all ▁spirits ▁are ▁entirely ▁benef icial ▁in ▁nature . ▁F ocus es ▁are ▁completed ▁over ▁time ; ▁only ▁one ▁focus ▁may ▁be ▁worked ▁on ▁at ▁once , ▁and ▁working ▁on ▁one ▁cons umes ▁some ▁political ▁power . ▁Initial ly , ▁only ▁a ▁hand ful ▁of ▁key ▁nations , ▁like ▁Naz i ▁Germany , ▁the ▁United ▁Kingdom , ▁the ▁Soviet ▁Union , ▁and ▁the ▁United ▁States , ▁had ▁unique ▁focus ▁trees ; ▁all ▁other ▁nations ▁shared ▁a ▁generic ▁one . ▁Sub sequ ent ▁updates ▁and ▁D LC s ▁have ▁added ▁focus ▁trees ▁to ▁other ▁nations ▁as ▁well . ▁ ▁He arts ▁of ▁Iron ▁IV ▁also ▁introdu ces ▁the ▁concept ▁of ▁" world ▁t ension ," ▁an ▁abstract ▁representation ▁of ▁how ▁close ▁the ▁world ▁is ▁to ▁war ▁on ▁a ▁scale ▁from ▁ 0 ▁to ▁ 1 0 0 . ▁Ag gress ive ▁actions ▁by ▁any ▁nation ▁can ▁increase ▁world ▁t ension , ▁while ▁peace ful ▁actions ▁can ▁decrease ▁it . ▁Depending ▁on ▁the ▁circumstances ▁of ▁a ▁nation , ▁like ▁their ▁ide ology , ▁a ▁certain ▁level ▁of