NATO Secretary-General Jens Stoltenberg said on Tuesday that the alliance is seeking details on US President Donald Trump’s decision to cut US troops numbers in Germany.

Trump has criticized Germany for not spending more on defense, and on Monday confirmed last week’s reports of a cut of 9,500 troops.

“It’s not yet decided how and when this decision will be implemented,” Stoltenberg told a video news conference. He had spoken to Trump, as well as other US officials, and was also consulting with German Defense Minister Annegret Kramp-Karrenbauer, who said last week she had not been informed of the decision, Reuters reports.

“It’s a bilateral arrangement between the US and Germany but of course it matters for the whole alliance,” Stoltenberg said. He added he told Trump that US troops in Europe were not only protecting territory but allowing the US to project power beyond the continent.