THE olive branch which has extended to his summer stayaways comes with significant terms and conditions attached.
If James McCarthy, Marc Wilson and Darron Gibson -- the three players named by the Italian yesterday -- ignore the warning, it's safe to say they can forget about their international futures under this regime.
Anthony Stokes -- the 'tired' Anthony Stokes -- was the only really notable omission from the squad for the August 10 encounter with Croatia which was named in Ennistymon as part of the FAI's week-long AGM celebrations.
McCarthy, Wilson and Gibson all made the cut despite the contentious nature of their absences from the games in May and June, where four victories were secured against the backdrop of manager and senior player anger over those who stayed away.
What is apparent is that if they pull out again without an acceptable excuse, or through improper channels, they will be kicked to the kerb.
"We cannot find ourselves in this situation again," declared Trapattoni, "This is the last time that those players will be allowed to behave like that. I don't want to be betrayed.
"This time, I will send them the SMS. Do you wish to come, or do you prefer to stay at home? We can play with another team, no problem."
Strong words indeed. The controversial withdrawals of the youngsters from the Four Nations conclusion, the qualifier in Macedonia and the friendly with Italy in Belgium clearly infuriated the 72-year-old.
It was the manner in which it was handled that appears to have annoyed the Italian as much as their unavailability itself.
McCarthy cited an ankle problem, yet Trapattoni was unhappy that the Wigan midfielder failed to return calls from an FAI staff member. Gibson's groin excuse was treated sceptically, while Wilson simply failed to show up.
In that context, he feels the ultimatum is justified considering that, ostensibly, their inclusion in the squad is an act of forgiveness.
"There is one reason why I called them up," he continued. "It's important that we build a squad, and there is a basis for a good squad in the future. We need these players.
"Yes, I know that these players are busy in their clubs. But I was a player, I was in the national team, and we always had the mentality for our club and country.
"My disappointment (in May) is that I always defend my players, and praise them for their attitude, for their pride, for their mentality. I put myself on the line all the time by defending them. Now they must answer us for this reason. I give them trust.
"That is very important. I've had some of the greatest players, and they have professional respect for their club and for their country. These players have to confirm they have the right attitude; otherwise I will have to take back everything I said about them."
However, the timing of the Croatian encounter at the Aviva Stadium screams danger. The game takes place just three days before the start of the new Premier League season and clubs will be none too happy about the risk of losing key performers at such a vital juncture.
It is not unreasonable to suggest that pressure will be applied on individuals to give it a miss, with those close to McCarthy indicating that employer advice was central to his international no-shows, given that he was troubled by an ankle problem last term.
Nevertheless, Trapattoni has said in the past that he will be amenable to clubs' wishes around friendly games, if they would prefer a particular star to be involved for just 45 minutes or sometimes even less.
What he wants is a show of desire from those who have yet to fully establish themselves in the senior international set-up.
It's the persistent confusion that is a bugbear, feeding the suspicion that players are casual about their commitment to the cause because of some of the sacrifices involved.
"I know there have been a few misunderstandings," said Trapattoni, without citing an example. "It's just about making it clear, and being clear -- I want to come or I don't want to come -- it's simple.
"They have many games in their clubs and sometimes, okay, they are not happy to come and spend eight days with us. Okay then, stay at home. You don't want to come for a week with the national team? Okay, we know what players we have. We'll build another team.
"This is the squad, and that is clear. There is an injury, or there isn't. But not disappearing. That's just bad manners."
The general issue of discipline is another theme, a recurring topic highlighted again by reports of a late-night clash between a senior star and a non-playing member of the party in the lead-up to the Macedonian game.
Trapattoni didn't seem too perturbed by the topic and effectively glossed over it, stating only that he was seeking clarity about what actually unfolded, while confirming that he had allowed the players out on the evening in question. He seems resigned to the Irish habit that boys will be boys -- once the time is right.
"If a player wants to misbehave, they will do it anyway," he said. "It's important that we give them trust. After the game, it's possible that they can drink the beer in the bar."
Of course, when a team is winning their social decisions seem less important, and the impressive win in Skopje has put Ireland in a strong position to make next summer's Euro 2012 finals.
Trapattoni -- who is unsure if he will attend the World Cup 2014 qualifying draw in Rio de Janeiro on July 30 -- is conscious that he requires a successful finish this autumn if his contract is to be extended until that tournament although, with trademark charm, he mentioned that he can "watch elsewhere" if it drags on.
"If the FAI say bye bye, it is no problem," he stressed.
Should Wilson, McCarthy and Gibson fail to show for the Croatian gathering, Trapattoni will be delivering them a similar message.