Academy from Qatar on 14 December 2009. He moved up front for a second match against the Qatari side two days later and scored Ireland's only goal in a 3–1 defeat. He marked the last of his six appearances for the under-15s with a brace of goals in a 5–0 win against Northern Ireland. He made the step up to the under-16s at a tournament in Italy in October 2010, playing in all three matches against Ukraine, Italy and Denmark. His first goal for the under-16s came in the first of two fixtures against Hungary on 23 November 2010, the first in a 2–1 win. He missed the team's trip to Turkey in March 2011 after being selected for the under-17s' 2011 UEFA Under-17 elite round matches against Denmark, Greece and Latvia, but returned to captain the side in a double-header at home to Belgium in April 2011, his final under-16 appearances. Byrne made his under-17 debut in a tournament in Hungary in August 2010, giving Ireland the lead against the host nation in the semi-finals, only for Hungary to equalise and go on to win 4–2 on penalties. Ireland then lost to Serbia in the third-place play-off and finished fourth in the tournament. His impressive performances in Hungary meant he was retained in the squad for the 2011 UEFA Under-17 qualifiers against Norway, Albania and group hosts Malta. He appeared as a substitute in the wins against Malta and Albania that sealed Ireland's qualification to the elite round, but despite starting against Norway, he was unable to prevent defeat and Ireland finished second in the group. After a double-header in Italy in February 2011, Byrne played in all three UEFA Under-17 elite round matches against Denmark, Greece and Latvia, only for the undefeated Irish to miss out on the finals after Denmark beat Greece with a last-minute goal. As an early starter in the under-17s, Byrne was able to continue in the side for a second year, starting with a double-header against Serbia in September 2011. He then played in all three of Ireland's 2012 UEFA Under-17 qualifiers against Liechtenstein, Kazakhstan and the Czech Republic in October 2011, scoring a hat-trick in an 8–0 win against Liechtenstein. After drawing with Kazakhstan and losing to the Czech Republic, Ireland qualified for the elite round ahead of Kazakhstan on goal difference. After a training camp in Portugal in February 2012, Byrne