MEGADETH frontman Dave Mustaine, who last year revealed his "birther" opinions on a Canadian talk show, saying he doubted President Barack Obama was born in the United States, has thrown his weight behind yet another conspiracy theory — this time involving "chemtrails."

The "chemtrail" conspiracy theory holds that some trails left by aircraft are chemical or biological agents deliberately sprayed at high altitudes for purposes undisclosed to the general public in clandestine programs directed by various government officials. This theory is not accepted by the scientific community, which states that they are just normal contrails, short for "condensation trails," as there is no scientific evidence supporting the chemtrail theory.

In two separate tweets on Saturday (January 5), Mustaine wrote: "Shame on the pilots spraying the grid lines in the once beautiful skies of San Diego. Shame, shame, shame! It's aluminum oxides & barium salts. They know what their cargo is. Only a fool or an accomplice would argue the unarguable. #chemtrails"

Mustaine made headlines last August when he said on stage during a concert in Singapore that Obama was behind recent shooting rampages near Denver and Milwaukee. He continued his diatribe by wondering where he was going to live "if America keeps going the way it's going, because it looks like it's turning into Nazi America."