According to WSJ sources, he discussed this with Trump.

SpaceX founder Elon Musk ordered a slowdown of Starshield, the military version of Starlink satellite communication, on which Ukraine depends, writes Dozhd, citing The Wall Street Journal, which in turn refers to American officials and informed sources.
According to them, this decision caused panic in Kyiv and confusion in the Trump administration.
Two WSJ interlocutors claim that Musk and Trump discussed the restrictions by phone shortly after they became known.
According to one of them, they also talked about it before the decision – some officials believe that Musk acted alone, but another source for the newspaper said that before introducing the restrictions, Musk contacted several high-ranking representatives of the administration, including Trump.
When the scandal erupted, SpaceX representatives called the White House to develop a common position – the company and the administration had agreed on the decision in advance.
Musk himself wrote on X that the restrictions are determined by the American military and ultimately the president. Trump stated on Monday that he does not know who is behind it.
The restrictions began on October 14. According to the newspaper, because of them, some Ukrainian attack drones and interceptor drones became practically useless, and Ukrainian officials stated that it became easier for Russian missiles to bypass air defense.
Shortly before this, Musk and Trump publicly expressed outrage over Ukraine's strikes on Russian oil refineries, which the US president links to high energy prices. On October 10, Trump demanded that Zelensky stop such strikes, and Musk replied that the Ukrainian president "went too far."
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Заўжды ў нашым цэху прынята даваць спасылку на першакрыніцу, а не на перапосты. Упэўнены, што акрамя "Дождя" гэтую інфу разабралі і шмат іншых рэсурсаў, і не расійскіх, але і ўкраінскіх і розных іншых. Чым вас зацікаўлівае "Дождь"?