Iranian Supreme Leader Ayatollah Ali Khamenei appeared to express a confrontational attitude Sunday, just ahead of a new round of talks with Western nations over Iran’s nuclear program, touring an exhibition of surface-to-surface missiles, drones and other weaponry.

World powers, Khamenei scoffed, “expect Iran to limit its missile program while they continue posing military threats against Iran, and hence, such an expectation is foolish and silly.”

Iran’s ballistic program has also been a concern for the West since ballistic missiles could be used to deliver nuclear warheads. Iran insists the missile program has no nuclear dimensions but is also adamant that its defense industry is a “red line” as a topic at the nuclear talks.

The US has argued that a UN Security Council resolution bans Iran from “undertaking any activity related to ballistic missiles capable of delivering nuclear weapons.”

The Sunday remarks by Khamenei came during his visit to an aerospace exhibition in which

According to the semi-official Fars news agency, Khamenei was touring an exhibit of the Islamic Revolution Guards Corps (IRGC) Aerospace Force.

“The IRGC Aerospace Force should precisely advance its works and plans and should not be satisfied with its status quo,” Khamenei said. “This issue is a duty and all military officials should channel their efforts onto this path and government officials should also view this as among their main duties.”

An advanced CIA spy drone, captured in 2011 by Iran, and its Iranian-made copy were on display. The report said aerospace experts briefed Khamenei on the latest details of a project to reverse-engineer the drone.

Also on Sunday Iran’s president said his country would not surrender what it considers its right to nuclear development in upcoming talks with world powers, but that it would be “transparent” in negotiations over the contested program.

The talks, resuming Tuesday, face an informal July deadline to hammer out a final deal to limit Iran’s ability to build nuclear arms in exchange for ending crippling economic sanctions it faces.

While President Hassan Rouhani and Iran’s negotiators have the backing of Khamenei, hard-liners increasingly criticize the deal as giving up too much while gaining too little from the West.