After the Pulwama attack, the Indian Air Force carried out airstrikes deep inside Pakistan territory to neutralise Jaish-e-Mohammad terror bases. IAF went all the way up to Balakot, which is only a few kilometres away from Abbottabad, where Osama Bin Laden was killed by the USA. Following this, Pakistan resorted to heavy shelling on the Line of Control and also infiltrated Indian airspace today, as a consequence of which, news has emerged that one of their F16s have been shot down.
Following Pakistan’s misadventure, TimesNow has now reported that the United States of America has cautioned Pakistan against using American defence equipment without its permission. The F16s are also American fighter jets that were sold to Pakistan.
— TIMES NOW (@TimesNow) February 27, 2019
The USA has a strict end-use monitoring agreement where the F16s supplied to Pakistan cannot be used to escalate. At best, the F16 can be used to defend itself and in this case, Pakistan used it to breach Indian airspace and was subsequently shot down. Pakistan has apparently done so without the permission of the USA and hence, this warning has been issued to Pakistan.
Even in 2016, when Pakistan was contemplating buying the F16 from another country other than the USA, US State Department had said that under the US law, any retransfers of US-origin defence items to a third party require approval from the US government and would be subject to end-use monitoring.
It hence stands to reason that the USA has the authority to ban Pakistan from using the F16 for purpose of aggression and escalation, as it seems to have done now.