Britain on Friday named Jonathan Powell, who was chief of staff to former prime minister Tony Blair, as its national security adviser, a role that will involve responding to global threats and building ties with Donald Trump’s new U.S. administration.

Powell, who also served as a diplomat in Britain’s Foreign Office for 10 years, played a major role in negotiating the Good Friday Agreement of 1998 which largely ended three decades of sectarian violence in Northern Ireland.

Prime Minister Keir Starmer said Powell’s experience working on some of the world’s most complex conflicts meant he was “uniquely qualified” to advise on dealing with security challenges and building ties with foreign governments.

Powell said he was honoured to accept the role. “National security is at the heart of this country’s response to the many challenges we face and having an integrated response will be crucial to our success,” he said.

The 68-year-old currently leads Inter Mediate, a charity working on resolving international conflicts. He was recently appointed as the government’s special envoy for negotiations that led to the return of the Chagos Islands, a chain of islands in the Indian Ocean, to Mauritius.

Former prime minister Rishi Sunak announced in April that Gwyn Jenkins, one of the country’s top generals, would be the next national security adviser, but that decision was overturned by Starmer, who won a landslide election victory in July.

Powell will succeed Tim Barrow, who has served in the role since September 2022.

Starmer and foreign minister David Lammy — who has criticised Trump in the past — are now seeking to build ties with the U.S. president-elect’s team.

There are a number of areas where the British government could clash with the incoming Trump administration, from Ukraine to China.

Britain has been one of Ukraine’s staunchest allies in its conflict against Russia and Trump’s victory raises questions over future U.S. support to Kyiv, while Starmer’s decision to reset ties with China could be challenged by Trump, who pressured Britain to take a much tougher approach in his first term.