Northern Ireland terror threat level raised to 'severe' ahead of potential Biden visit.

MI5 has raised the terrorism threat level in Northern Ireland to "severe" due to an increase in activity by dissident Irish republican militants. The threat had stood at "substantial" for the past year. Small Irish Republican Army splinter groups have continued to launch sporadic attacks on security forces. The change to the threat level comes ahead of events commemorating the 25th anniversary of the Good Friday agreement. The threat level for the rest of the U.K. remains at substantial.