In 1997, Ireland changed its immigration legislation to allow immigration officers to examine (i.e. request identity documents from) travellers arriving in the state by sea or air (from elsewhere in the CTA) and to refuse them permission to land if they are not entitled to enter. Although formally this applies only to people other than Irish and British citizens, both of the latter groups are effectively covered as they may be required to produce identity documents to prove that they are entitled to the CTA arrangements. while targeted controls are conducted along the land border in what are referred to as "intelligence driven operations". Air passengers arriving at Irish ports/airports from elsewhere in the CTA are no longer channelled separately from those arriving from outside the CTA; consequently all sea and air passengers must pass through Irish immigration checks, administered by the Garda National Immigration Bureau (GNIB). While British citizens are not required to be in possession of a valid travel document as a condition of entry, they may be required to satisfy immigration officials as to their nationality.