Learn Portuguese (Portugal): Quem provocou o desastre foi a liderança. - The one who caused the disaster was the leadership.

This structure is used to add strong emphasis to the subject. By starting with Quem (The one who) and placing foi (was) right before a liderança, it singles out the leadership as the specific culprit. It translates closer to 'It was the leadership who caused the disaster'.

If the sentence ended with a plural subject like os líderes (the leaders), would the verbs change?

The verb immediately following Quem is always in the third-person singular, so provocou would stay the same. However, the verb ser (here, foi) generally agrees with the subject it introduces. So, you would say: Quem provocou o desastre foram os líderes.

Why is provocou translated here as 'caused' instead of 'provoked'?

While provocar does mean 'to provoke' (like a reaction or an argument), it is also the standard verb in Portuguese for 'to cause' or 'to bring about' when talking about accidents, disasters, or physical damage. You could also use causou, but provocou is very natural and common in this context.

Why are both provocou and foi in the same past tense?