Meaning trap
break up
disrupt a gathering
To cause a group of people who have gathered together, especially for a meeting, protest, or other event, to disperse or stop their activity, often by force or official order.

Don't mix these meanings
Same phrase, different job.
To cause a group of people who have gathered together, especially for a meeting, protest, or other event, to disperse or stop their activity, often by force or official order.
'break up' also has the more basic meaning 'end a romantic relationship'; this is the advanced sense.
Hear it in context
Notice where the phrase sounds natural.
The police were called in to break up the demonstration before it turned violent.
In some countries, the government may break up public gatherings if they are considered a threat to security or public order.
Fix the pattern
One small grammar move makes it sound right.
Not: Security broke up it.
Say: Security broke it up.
With a pronoun, the object goes in the middle: 'break it up'.
Which sounds natural?
Tap the one a native speaker would say.
'Break up' is the natural verb for forcing a crowd to disperse; 'dispersed the crowd' is formal.
Build natural chunks
Words that usually travel with it.
break up + gathering
- the fight
- the crowd
- the party
- the protest
Don't confuse it
Related
Other meanings and phrases to compare.
- break up (end a romantic relationship) — 'break up' also has the more basic meaning 'end a romantic relationship'; this is the advanced sense.