On September 13, 2015, the office of Iranian Supreme Leader Ali Khamenei shared via its official Twitter account a video on the office's YouTube channel titled "If Any War Happens..." in which Khamenei warned that the "invading and criminal America" will "leave the war arena defeated."
The video, which is 1:43 in duration and accompanied by some English subtitles, opens by showing U.S. President Barack Obama stating that the U.S. will not have a problem "knocking out [Iran's] military with speed and dispatch if we choose to." In response, Khamenei, in a July 18, 2015 address, calls this threat by Obama "nonsense stemming from ignorance." Khamenei goes on to advise the Americans to "use their experiences [in the Middle East] correctly" as images play in the background: a swift boat attack on an American aircraft carrier, photos of the advanced American RQ-170 drone that Iran brought down on its soil, a photo of Hizbullah leader Hassan Nasrallah against a backdrop of a missile flying the Hizbullah flag, photos from the 2006 Lebanon war, Khamenei delivering a speech to soldiers from Iran's Islamic Revolutionary Guards Corps (IRGC), Iranian missiles being launched and striking ships, bodies of American soldiers returning from Iraq, and a photo of Khamenei leading Iran's top military echelon as a crowd calls "Khamenei is the leader."
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Khamenei is then heard to say: "We will not be the first to [launch] any war, we do not welcome any war. But if any war happens here, the invading and criminal America will be the side that will leave the war arena defeated." In the background a crowd calls "We will stand until the end, Khamenei is the leader."
The following is the video:
 See MEMRI TV Clip No. 5011, Iranian Supreme Leader Khamenei Reaffirms "Death to America" Slogan, Calls to Bring U.S. Leaders to Trial, July 18, 2015.