The US State Department is said to have reprimanded Pakistan for misusing fighter jet F-16s in a written letter which details American concerns about how Pakistan fielded American-made fighter jets after a skirmish with India over Kashmir.A top American diplomat sent a written reprimand to the chiefs of the Pakistani Air Force in August, 2019, accusing them of misusing US-supplied F-16 fighter jets and jeopardizing their shared security, according to documents obtained media group US News & World Report.

The said communication came months after India claimed one such F-16 shot down one of its fighter jets during a days-long skirmish in February 2019 over Pakistan-occupied Kashmir (PoK), which would amount to a fundamental violation by Pakistan of the terms governing the sale of its US fighter jets and a dangerous form of military escalation among nuclear powers. A source who viewed the letter, written by Andrea Thompson, then-under secretary of State for Arms Control and International Security Affairs, said the letter served as a direct response to US concerns about the F-16 use over Kashmir in February, though the letter itself does not specifically reference the incident.

Addressed to the head of the Pakistani Air Force, Air Chief Marshal Mujahid Anwar Khan, the letter began by relaying the State Department's confirmation that Pakistan had moved the F-16s and accompanying American-made missiles to unapproved forward operating bases in defiance of its agreement with the US. Using diplomatic language, Thompson, who has since left government, warned the Pakistani officials that their behaviour risked allowing these weapons to fall into the hands of malign actors and "could under mine our shared security platforms and infrastructures."

The letter represented the first admission since February from the US of its concerns about how Pakistan used its fleet of F-16s in stark violation of the original terms of the sale. A State Department spokes woman said in March this year that the department acknowledged the Indian reports of Pakistan's misusing the fighters in the February skirmish, adding "we're following that issue very closely."Several diplomatic officials and analysts with experience in Pakistan said it was not surprising that Thomps on did not expressly mention in the message US concerns about using the F-16s to shoot down the Indian fighter jet. Acknowledging in a formal State Department transmission such a clear violation of the congressionally approved terms forselling the fighter jets to Pakistan would likely have triggered formal procedures to reprimand Islamabad at a time the Trump administration is attempting to repair contentious relations with the ally.

Thompson, a career military intelligence officer who first entered the administration as Vice President Mike Pence's national securityadviser, admonished Pakistan in the letter for having "relocated,maintained and operated" the American made F-16s and the AMRAAM missilesthey use from forward operating bases not approved under the original terms ofthe sale. The former Army colonel, who left the White House in September, alsoexpressed concern at the access Pakistani officials allowed American weaponsinspectors.

"While we understand from you that these aircraftmovements were done in support of national defence objectives," Thompsonwrote in the letter, "the US government considers the relocation ofaircraft to non-US government authorized bases concerning and inconsistent withthe F-16 Letter of Offer and Acceptance."

"Such actions could subject sensitive US-technologiesto diversion to or access by third parties, and could undermine our sharedsecurity platforms and infrastructures," Thompson wrote.A flare-up inmilitary tensions between Pakistan and India began in mid-February, after aPakistan-based terrorist group claimed credit for a suicide bombing in Kashmirthat killed 40 Indian security personnel.

The Pakistani armed forces possess 76 American-suppliedF-16s – by far the most potent fighter jet in its military arsenal-- understrict rules imposed by the State Department, the Department of Defense andCongress. Among the rules are that Islamabad may only house the fighters andthe corresponding American missiles on two specific air force bases at Mushafand Shahbaz and that it only uses them for counter-terror operations, not againstforeign countries.

The agreement for their sale and subsequent operation,governed in part by the State Department's Defense Security Cooperation Agency,also stipulates that American contractors and mechanics must have access to thejets at any time of day or night both to help maintain them and to monitor howthe Pakistani military employs them.