For the second time in three years Iran unveiled an anti-aircraft missile system on Thursday, said to be produced to replace Russian-supplied S-300.

Bavar-373 (meaning Belief in Persian) was first unveiled in August 2016 in the presence of Iran’s President Hassan Rouhani.

Bavar-373 is a domestically produced long-range road-mobile surface-to-air missile system.

It is not clear why the same weapons system is unveiled for a second time, again in Rouhani’s presence. Three years ago when it was first shown to the media, Iranian news agencies said the missile system “was officially unveiled”.

Iran’s defense minister General Amir Hatami acknowledged the 2016 unveiling as “a quick overview” during Thursday’s ceremony. He also hinted at a final “complete” unveiling sometime in the future.

There have been instances in the past that Iran has unveiled drones and other weapons thought to be at their developmental stage and not ready for operational production.

As tensions have flared in the Persian Gulf since May, Iran has made sure to exhibit its military prowess. Om August 10 Iran unveiled the Falaq air defense system, which is also claimed to be a long-range weapon.

In June, Iran shot down a U.S. surveillance drone over the Persian Gulf, but Washington ignored the incident refraining from direct retaliation.