The United States on Thursday called the shooting of an American drone by Iran a “big mistake” and an “unprovoked attack”, disputing Iranian claim the aircraft had crossed into their airspace, but did not spell out consequences if any amidst escalating tensions in the region.“Iran made a very big mistake!” President Donald Trump wrote on twitter in his first public response to the shooting,, and repeated it in remarks to reporters with visiting Canadian Prime Minister Justin Trudeau.“This drone was in international waters, clearly. We have it all documented scientifically not just words. And they made a very bad mistake.”“We didn’t have a man of woman in the drone,” he added. “It would have made a big, big difference.” The United States has said, drawing redline for Teheran, the killing of even one American by Iran will be result in military counter-attack.Asked what happens next, the US president, said, “”Let’s see what happens.” But he repeated, possibly playing down the shooting, it was a mistake. “I find it hard to believe it was intentional … (it was someone) “loose and stupid who did it”.US military had earlier said in a statement the aircraft was in international airspace, disputing Iranian claims. “This was an unprovoked attack on a US surveillance asset in international airspace,” Bill Urban, a spokesman for the US Central Command, said in a statement.The Pentagon released a video of the shot drone over the Strait of Hormuz, and also gave more details to saying the aircraft was at least 34 miles from the Iranian coast at the time it was hit.The Central Command described the drone as Broad Area Maritime Surveillance (or BAMS-D, which is a RQ-4A Global Hawk High-Altitude Long Endurance (HALE) Unmanned Aircraft System (UAS) and added that it provides real-time intelligence, surveillance and reconnaissance.