Andy Burnham, Prime Minister of Britain, said he and other European leaders will travel to the United States next month to persuade Donald Trump, the president of the country, to hand over part of his Patriot air defense missile reserves to Ukraine before winter.

In an interview with Bloomberg in Kyiv, he said: “I’m looking forward to traveling to New York in September.” The trip coincides with the meeting of the United Nations General Assembly and will be his first trip to the United States after taking office as prime minister.

Burnham added: “I haven’t finalized the details completely yet, but I will probably go—especially after today’s conversation. By leaving here, it becomes completely clear what I have to do in the weeks ahead.”

Trump has backed away from his earlier promise to provide interceptor missiles or allow their production in Kyiv.