The US delivered long-range missiles to Ukraine earlier this month that the Biden administration had previously refused to send following a directive from President Joe Biden, the Pentagon said Wednesday.

Biden secretly approved the transfer of the long-range ATACMS missiles in February for use inside Ukrainian territory. The ATACMS missiles were then quietly included in the $300 million aid package announced on March 12 and ultimately delivered to Ukraine earlier this month, according to Pentagon spokesman Lt. Col. Garron Garn.

“It was not announced that we are providing Ukraine with this new capability at the time in order to maintain operational security for Ukraine at their request,” Garn said, deferring questions about their use to Ukraine’s military.

The Biden administration had resisted sending the long-range missiles in part because of readiness concerns. The powerful missiles require time and complex components to produce. Lockheed Martin, which manufactures the ATACMS missiles, is in full-rate production and produces approximately 500 missiles per year, a spokesman for the company said in September.

The US worked behind the scenes to address the readiness concerns, which included buying more ATACMS missiles and filling US military stocks.