Norway’s former Prime Minister Jens Stoltenberg has been chosen by NATO to be its next Secretary-General.

He will succeed Anders Fogh Rasmussen who tweeted his approval, saying the Ukraine crisis showed the need for continued strong and determined leadership.

Rasmussen, an ex- Danish premier, has led the Western military alliance since 2009.

Stoltenberg will take over in October, becoming the first Norwegian to occupy NATO’s top post.

It comes at a time when NATO, seen by some as a Cold War relic, has gained new relevance because of concerns about a newly assertive Russia following its annexation of Ukraine’s Crimea.

Stoltenberg will face a challenge in trying to persuade European countries to reverse, or at least end, sharp cuts in defence spending that many of them have adopted in response to the financial crisis.

He served for nearly 10 years as Norway’s prime minister before losing elections last September.

He was in office when far right militant Anders Behring Breivik went on a bombing and shooting spree in 2011 that killed 77 people.