"I can confirm that the United States provided Ukraine with long-range ATACMS at the president's direct direction," State Department spokesman Vedant Patel told reporters.

The Army Tactical Missile Systems (ATACMS) were part of a March aid package for Ukraine, not the one just approved by Congress and signed by President Joe Biden.

But "we did not announce this at the onset in order to maintain operational security for Ukraine at their request," Patel said, adding that the "missiles arrived in Ukraine this month."

Some ATACMS missiles can hit targets up to 300 kilometers (190 miles) away, and a Defense Department spokesperson confirmed that was the long-range variant supplied to Ukraine.

The White House said last year that the United States sent a shorter-range variant of ATACMS that can travel 165 kilometers, but the longer-range missiles were a long-standing request from Kyiv.

US National Security Advisor Jake Sullivan said the United States plans to send more of the long-range missiles to Ukraine.

"They will make a difference. But as I've said before at this podium... there is no silver bullet," Sullivan said.

The details on ATACMS came on the same day Biden signed a bill to provide $61 billion in new aid for Ukraine, clearing the way for the Pentagon to announce an assistance package featuring desperately needed artillery and air defense munitions.