Basically, Nawaz Sharif went to Saudi and without taking anyone's advice I.e. Parliament or Pakistans Army, he agreed to send troops to Yemen and provide Saudi with military weapons etc.
You must realise that Nawaz has a strong interest in Saudi and UAE because when he was exiled he spent a long time in Saudi but more importantly him and his elite corrupt friends have around $30 billion worth of assets in the Arab world hence they can't afford on a personal level to displease the Arabs.
When he came back to Pakistan, it is highly likely that the Pakistani army gave some signal to Nawaz saying to basically back off the whole Yemen thing. Nawaz sharif had to do this diplomatically and took the case to parliament whereby the majority voted against intervention.
This puts the elite corrupt in a difficult position now because they fear their assets being seized abroad. UAE knows this and therefore the threat was indirectly apparently to the leaders of Pakistan regarding their personal fortunes because other than that the most they can do is send a few thousand of our workers working there back home which wouldn't be too bad.
Now the problem is that the Arab nations know that out of all the Muslim nations Pakistan is arguably the strongest in terms of military capability. And many analyst suggest that the UAEs statement was influenced by a third party. Either Saudi, to put pressure on Pakistan. Or Nawaz, to try and win public support to intervene out of fear or something.
There's a lot more politics in this but that's just a brief summary.
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