Poland has called up the Chicago Fire and US men's national team goalkeeper, who turned 18 on Sunday, for UEFA Nations League matches in June. The development is expected since it was revealed last month that Poland national team coach Czesaw Michniewicz would pay a visit.

Slonina holds dual citizenship and played in World Cup qualifying for the United States as a reserve, though he has yet to play for the senior national team. He has the potential to become the United States' goalie of the future, but only if he commits to Poland long-term. Even if he accepted the call-up, he is unlikely to be permanently attached to the European country. He isn't obliged to make a FIFA one-time switch to play for Poland because he hasn't represented the United States in official competition at any level, and FIFA rules dictate that any player under 21 can participate in three matches—official or otherwise—before being cap-tied.

Slonina is one of five goalkeepers from Poland invited in for the forthcoming window, including Wojciech Szczsny of Juventus, Bartomej Drgowski of Fiorentina, Kamil Grabara of Copenhagen, and Ukasz Skorupski of Bologna. Poland will compete in League A, Group 4 of the Nations League, which serves as a warm-up for the World Cup, against Belgium, Wales, and the Netherlands. In Qatar, the Poles are part of a group that includes Mexico, Saudi Arabia, and Argentina.

Slonina is one of a handful of American artists that have been considering their overseas options. Rubio Rubin, a forward who earned seven caps for the United States Men's National Team between 2014 and 2018, had his transfer to Guatemala accepted on Tuesday.

Coach Gregg Berhalter of the United States has maintained his position that dual-national players should attend various camps and opportunities to absorb as much information as possible before making a decision on their international careers. Slonina may have to fly overseas next month as a result of this.