It appears the two sides are far from an agreement.
"He's not in training camp," Armstrong told the Blues' website. "We've worked in earnest with his representatives trying to get him into training camp. We've talked about a lot of different options as far as a number of years.
"[Tuesday] night, we gave it a last-ditch kick at the can around eight or nine o'clock at night and it didn't hold. So from this point forward, he's not in camp and we treat him like an injured player. ... If he misses a week, a month, a year, we're not really sure, but he's not here now and we have to move forward."
Armstrong was hoping to have a deal reached by the start of camp, and thought the team put its "best food forward to try and get something done."
So for the time being, talks have broken off between the two sides and the Blues will move forward without their top defenseman, who has 121 points in 224 career games.
"I probably had my best sleep last night than I've had in three weeks when I realized this deal wasn't going to get done because I felt that we had really had done what we could do to get it done, to get him in here today," Armstrong said. "Training camp's a very important time for a team. It wasn't able to get done, so now we move forward with the players that we have, and at some point we'll re-engage and see if there's a different option that wasn't there. We were focused in on a deal that had a lot of term. Maybe that's not going to happen. We'll have to find out."
Both parties want to get a long-term agreement ironed out, but a short-term deal, around two years, could be worked out once the two sides resume negotiations.
"At some point, Alex will sign here," Armstrong said. "There's really three options: He's going to sign with us, he signs an offer sheet or he doesn't play this year. Those are the three things. There's no fourth thing.
"He will be a Blue. I want to crystalize that for our fans and for 29 other poachers out there. He's going to be a Blue."