Unexplained Lights Recorded over Arizona

Four unknown bright lights flying in a square formation towards Yuma, Arizona were seen by numerous people a few days ago.

Witness: Yuma Proving Grounds does military testing but I’ve has never seen like this in all 23 years of living here, I wish I could’ve recorded the 4 flying in a square formation but I couldn’t pull my phone out fast enough after I was done being in awe.

So the question is what are/were they… aliens or maybe military test?