under the rule of

[navi tasan]

!) They were happy when Vietnam invaded Cambodia under Pol Pot.
2) They were happy when Vietnam invaded Cambodia under the rule of Pol Pot.

Are the sentences grammatical and do they mean what they are supposed to mean?

Cambodia was being ruled by Pol Pot when it was invaded by Vietnam. They were happy about the invasion.

If the sentences are fine, are 'under Pol Pot' and 'under the rule of Pol Pot' adjectival (modifying Cambodia) or adverbial? I'd say they are adjectival.

 

[Annabel Lee]

!) They were happy when Vietnam invaded Cambodia under Pol Pot.
2) They were happy when Vietnam invaded Cambodia under the rule of Pol Pot.

In both examples, the "under"-phrase strikes me as adverbial and as meaning that Vietnam, not Cambodia, was ruled by Pol Pot at the time of the invasion. The following would be clearer, I think. They use the passive rather than the active voice, and the "under"-phrase modifier in the "when"-clause precedes rather than follows the verb phrase in that clause:

3) They were happy when, under Pol Pot's rule, Cambodia was invaded by Vietnam.​

4) They were happy when Cambodia under Pol Pot was invaded by Vietnam.​