Members of  Anthrax , Slayer and Megadeth have said in interviews that they’d love to do a full-scale Big 4 tour in the U.S. in 2012. But there’s one key ingredient missing – Metallica – who have yet to commit to any more Big 4 concerts.

“It's funny that I've done 400 interviews, I guess, in the last month and that's the one question I've been asked in every interview. And I tell everybody, ‘What makes you think we have any say at all over what happens with the Big 4?,’" Anthrax guitarist Scott Ian tells SF Weekly.

“I mean, I get it; we're a part of it and all that, but Metallica is steering the ship. This is their thing. They installed this red phone with a big red ‘4’ at our manager's office and when it rings, you just say when and where.”

He continues, "If it were up to me, we'd do a hundred more Big 4 shows. I can only hope there's going to be more. All the guys in the bands want to do them, including the guys in Metallica, so that makes me think there will be more shows at some point. But as far as when and where, I don't have a clue."

Even if the Big 4 never reconvenes, the shows they did have had a substantial impact on the metal community. Now more than ever, there’s a renewed interest in thrash music. Fans are reaching into the back catalogs of the Big 4 as well as other classic thrash bands such as Exodus, Overkill, Testament, Pantera, Sacred Reich, Flotsam & Jetsam and Death Angel. And they’re also discovering new thrash bands, including Warbringer, Municipal Waste, Toxic Holocaust, Lazarus A.D. and Evile.

“We just started having conversations with our agent about how we were going to kick it off for [our new record ‘Worship Music,’] and the idea was floated to us. ‘How about Testament?’ And everyone just instantly said yes. We just thought it was a great idea. They've been back on the scene for a few years now, and their last album did really well. It just seemed like a great thing to go do."

Anthrax's co-headlining tour with Testament recently launched and is scheduled to through a Nov. 19 show in Milwaukee. Click here for a full list of dates.