French President Emmanuel Macron pressed Europeans to strengthen the cooperation in security and sharing of intelligence after the deadly attack in Manchester on Monday night, as he arrived in Brussels for a meeting of the NATO on Thursday.

The 39-year-old President, a newcomer to international diplomacy, will meet many of his counterparts for the first time over the next few days at the NATO meeting in the Belgian capital followed by a G7 summit in Sicily.

Welcomed by Belgian Prime Minister Charles Michel at his Brussels residence, Mr. Macron promoted what he calls his “protection agenda” for Europe which, he said, must include measures to protect workers from the effects of globalisation but also to beef up cooperation to prevent further attacks.

“Our British friends have, a few days ago, gone through what our two countries have gone through over the last few months, with the terrorist threat in Manchester,” Mr. Macron said at a joint news conference with Mr. Michel.

“Beyond solidarity, it’s obviously European cooperation that we need to reinforce, in the field of intelligence, information sharing, the protection of our common borders,” said Mr. Macron, who was elected just over two weeks ago.

British officials have expressed frustration over leaks to the media in the United States on their investigation into Manchester suicide bombing, which killed 22 people and, according to a British counter-terrorism source, they have stopped sharing information on the bombing with the U.S.

Mr. Macron will meet his U.S. counterpart Donald Trump for the first time at an informal lunch later that will immediately test his diplomatic skills, given the unpredictable nature of the U.S. leader.

The French President will also meet his Turkish and Polish counterparts and European Commission President Jean-Claude Juncker.