Jonathan Powell, the former chief of staff to Tony Blair, has been appointed by UK Labour leader Sir Keir Starmer as his national security adviser.

Powell, who played a key role in the 1998 Good Friday Agreement in Northern Ireland, will take over from Sir Tim Barrow next month.

The appointment arrives at a critical juncture, with ongoing conflicts in the Middle East and Ukraine, and Donald Trump's impending return to the White House in January.

Sir Keir highlighted Powell's unique qualifications to advise on global security issues.

Alongside Powell, Liz Lloyd, another former Blair aide, will become the director of policy delivery and innovation.

Traditionally, the national security adviser is a civil servant, but Powell will be a special adviser, a political appointee, paid by taxpayers.

The role's appointment by Sir Keir follows the cancellation of a previously announced appointee, General Gwyn Jenkins, a decision made without explanation.

Powell has also been involved in recent negotiations concerning the Chagos Islands’ sovereignty transition to Mauritius, a deal criticized by Conservative MPs and some US Republicans.

Powell defended the UK's decision, citing international legal rulings, and emphasized the involvement of all necessary US agencies in the negotiation process.

Critics, including former foreign secretary James Cleverly who was part of the original talks, oppose the deal, suggesting it diminishes Britain's overseas territories.

Jonathan Powell previously served as the UK envoy to Libya and has led a charity focused on international conflict resolution.