Washington is taking a close look at reports that Pakistan used US-supplied F-16 fighter jets in the recent confrontation with India, according to State Department Deputy Spokesperson Robert Palladino.

“We’ve seen those reports and we’re following that issue very closely,” Palladino told reporters at a Department briefing on Tuesday in Washington. “We’re taking a look and we’re going to continue to take a look”.

However, he added that he could not confirm anything because “as a matter of policy, we don’t publicly comment on the contents of bilateral agreements that we have in this regard involving US defence technologies nor the communications that we have with other countries about that”.

“We reiterate our call for Pakistan to abide by its UN Security Council commitments to deny terrorists sanctuary and to block their access to funds”, Palladino said.

He said that a “lot of” private diplomacy was taking place between US and India and Pakistan in addition to ongoing high-level contacts through the embassies in Washington and in New Delhi and Islamabad to ease the tensions.

This comes after India gave proof to the US about the use of F-16 fighters and AMRAAM beyond visual range air-to-air missile by Pakistan during its unsuccessful aerial raid targeting four Indian military installations on February 27.

Official sources said India was confident that Washington was carrying out a thorough investigation into the use of the US-manufactured fighter as well as the missile onboard it in the offensive operation against India.

On Thursday, Air Vice Marshal RGK Kapoor said in New Delhi that Pakistan sent F-16s, JF-17 Thunders and Mirages last Wednesday to the Line of Control (LoC) in Kashmir and an F-16 was shot down by the Indian Air Force (IAF).

The IAF on February 28 displayed a piece of an AMRAAM missile which landed in an Indian military compound when Pakistan launched an attack along the LoC. Of the jets in Pakistan’s arsenal, the AMRAAM can be used only with F-16. The IAF also said it identified F-16s operating there through their electronic signatures.

As part of the purchasing agreement, the US had put restrictions, the US had reportedly barred Pakistan from using the F-16s against any third country and it was only allowed to operate the fighter in self-defence and for anti-terror missions.

AMRAAM missiles allow a fighter pilot to target an enemy aircraft that is beyond visual range, in day or night, and in all-weather conditions. They have an autonomous guidance capability, which allows the pilot to manoeuvre immediately after the missile’s launch.

Pakistan has categorically said that no F-16 fighter jets were used in the aerial combat against India.

On Monday, Pakistan’s Ambassador Asad Majeed Khan said at a Washington think tank, “I am not aware of request from the US side about the F-16s”.

Short for Advanced Medium-Range Air-to-Air Missile, AMRAAM missiles were obtained by Pakistan from the US in 2010.

Its manufacturer Raytheon says that it has an “advanced active guidance” system and its design “allows it to quickly find targets in the most combat challenging environments”.

Pakistan has bought several batches of F-16 planes since 1982, and 85 of the jet made by Lockheed Martin Corp are estimated to be in the Pakistan Air Force (PAF) fleet.

In 2016, the US Congress ended subsidies for F-16 sales to Pakistan.

The US State Department has said that America is seeking more information from Pakistan on the potential misuse of American-made F-16 fighter jets by it against India in violation of the end-user agreement.

After the Pulwama terror attack, India on February 26 carried out “non-military pre-emptive” airstrikes targeting the JeM training camp in Balakot in Pakistan’s restive Khyber Pakhtunkhwa province, about 80-km from the Line of Control (LoC), reportedly killing a “very large number” of terrorists, trainers and senior commanders.

The next day, Pakistan Air Force tried to target Indian military installation in Kashmir but was thwarted by the IAF which lost a MiG-21 while its pilot Wing Commander Abhinandan Varthaman was captured. However, amid immense global pressure, he was handed over to India on Friday.