Prosecutors say a Vietnamese man accused of plotting with an al-Qaida off-shoot to bomb London's Heathrow Airport should get 50 years in prison.

Minh Quang Pham faces sentencing May 16 after pleading guilty to terrorism charges in January. Pham admitted supporting al-Qaida in the Arabian Peninsula.

The Heathrow plot was never carried out. Pham was arrested at the airport when he returned in July 2011 from a six-month Yemen trip.

Prosecutors say al-Qaida in the Arabian Peninsula has called on followers to attack civilians and has taken credit for coordinating attacks overseas. Those attacks include the January 2015 Paris attack on the French publication Charlie Hebdo. A dozen people died.

Pham's lawyer says his client had no intention of carrying out violence and shouldn't serve over 30 years in prison.