It was 1 April 2018 – Easter weekend – and Xu Yanjun was amid the bustling bars and restaurants in the Sainte Catherine district of Brussels, not far from the Grand Place.
He had flown into Amsterdam and then driven into Belgium for the first part of his European holiday.
But he was no tourist, according to the US authorities.
Xu had allegedly come to meet an American employee of GE Aviation – a specialist on aircraft engine design. The company had spent decades and millions of dollars developing composite materials which allowed lighter, sturdier and cheaper fan blades and cases inside engines.
Xu was expecting the American to hand over secrets, according to a US indictment. That was because, the US authorities allege, Xu was a spy for the Chinese Ministry of State Security (MSS).
But he was in for a surprise.