In 2012 and 2013, Van Leeuwen was part of the management team of an integrated police training mission by the Dutch government in the Afghan province of Kunduz during the war in that country. He subsequently worked as the consul-general of the Dutch consulate-general in Mumbai, and he was appointed ambassador to Afghanistan in 2016.[3][4] He returned to the Ministry of Foreign Affairs in The Hague in 2018 to serve as Director Middle East and North Africa.[3]
Van Leeuwen became a counselor to Prime Minister Mark Rutte on foreign affairs and defense issues at his Ministry of General Affairs in October 2020.[3][4] On 4 December 2023, he was sworn in by King Willem-Alexander as Minister for Foreign Trade and Development Cooperation as a result of the maternity leave of Liesje Schreinemacher, who became the first Dutch minister in history to take such a leave. Van Leeuwen is a member of the conservative-liberal People's Party for Freedom and Democracy (VVD).[4][5] Schreinemacher returned to the position on 15 April 2024.[6]