WASHINGTON—Bipartisan lawmakers are calling for an investigation into Elon Musk after The Wall Street Journal reported that the SpaceX chief restricted Ukraine’s access to the company’s satellite-based Starlink network.

Republican Rep. Brian Fitzpatrick of Pennsylvania said Congress should call Musk and other witnesses to testify under oath. “We got to investigate,” he told CNN on Tuesday. “We got to call the witnesses, got to bring them in, put them under oath and get to the bottom of it because this is a very, very serious matter.”Fitzpatrick also said Congress could block funding for any federal agencies or agency heads that played any role in throttling the network.

Democratic Sen. Adam Schiff of California also called for an investigation by the Senate and for Musk to testify under oath. “National security decisions should be made in our national security interests, and not based on the personal whim of an unstable executive,” he said in an X post Tuesday.

Sen. Chris Coons, a Democrat from Delaware, last week said he was considering subpoenaing Musk or Defense Secretary Pete Hegseth to testify about the Starlink issue if Democrats win control of the Senate in the midterm elections. On Tuesday, after the Journal reported that Musk ordered the throttling of Starlink, Coons raised concerns about a single individual—Musk—having control over such a strategically significant technology.

“We should be asking hard questions about why this one man has the same power of one of our four-star generals in terms of the outcome of a conflict halfway around the world, where our interests are aligned with Ukraine, not with Russia,” Coons said on MSNOW.

Musk said Wednesday on X: “Some fools still think the legacy news is real. Amazing.”It wasn’t immediately clear if he was referring to the Journal’s report. SpaceX, which operates Starlink, didn’t immediately respond to a request for comment.

In recent days, Ukraine has been grappling with the slowdown of the service, which makes it harder for Kyiv to intercept Russian attacks or launch drone strikes. Last week, Musk capped the speeds at which Ukrainian hardware could stay connected to the satellite-based network, the Journal reported. The speed restriction came after both Musk and President Trump expressed anger at Ukraine for attacking Russian diesel refineries. Musk and Trump also spoke in the hours after the Starlink slowdown became public, the Journal reported.

Bipartisan lawmakers supportive of Ukraine have been seeking information on how and why Starlink slowed down. Republican Sens. Thom Tillis of North Carolina, Lisa Murkowski of Alaska and John Cornyn of Texas, along with a few Democratic colleagues, last week called on the Inspector General of the Department of Defense to investigate whether the Pentagon or its contractors had a role in the speed restrictions on Starlink. The Pentagon’s Office of the Inspector General said it is in the process of preparing a response.