The United Kingdom has detained the first group of migrants arriving on small boats under a new bilateral agreement with France, known as the 'one in, one out' deal. This arrangement allows the UK to return undocumented migrants who cross the English Channel back to France. British Interior Minister Yvette Cooper confirmed the detentions, marking the initial enforcement of the treaty aimed at managing migration flows between the two countries. The detained migrants could be deported to France within weeks as part of the agreement. The deal has been publicly acknowledged by UK officials and reported by multiple news outlets in both the UK and France.