The United States has secretly shipped long-range Army Tactical Missile Systems (ATACMS) to Ukraine, which the Ukrainian military has already used twice against Russian forces in the past week, according to three U.S. officials. The revelation comes as President Joe Biden signed into law a foreign aid package providing billions of dollars in weapons and support to Ukraine, Israel, and Taiwan.

The first strike using the U.S.-provided ATACMS occurred on the morning of April 17, targeting a Russian military airfield about 100 miles inside Crimea's border. The second strike took place Tuesday night, targeting Russian forces east of the southeastern Ukrainian town of Berdyansk in Zaporizhzhia Oblast, officials said.

A National Security Council spokesperson confirmed that the U.S. has provided the long-range missiles to Ukraine, which were part of a $300 million military aid package unveiled on March 12. The administration did not reveal the inclusion of ATACMS at the time for operational security reasons, as President Biden had directed his national security team to send them secretly.

The ATACMS have a range of up to 300 kilometers (about 187 miles), allowing Ukraine to strike Russian military targets throughout Crimea and in occupied parts of eastern Ukraine that were previously difficult to reach. The U.S.-provided missiles included both warheads with cluster munitions and unitary blast fragmentation.

The Biden administration is already preparing another military aid package for Ukraine worth more than $1 billion, according to two U.S. officials familiar with the planning. The package will include a range of equipment that the U.S. has already provided Ukraine, such as ammunition, stinger missiles, artillery rounds, infantry fighting vehicles, and other military equipment.

The decision to send the long-range missiles comes after months of debate within the Biden administration. Officials had previously resisted sending the ATACMS out of concern that Ukraine would use them to strike inside Crimea or Russia, potentially prompting Russian President Vladimir Putin to escalate the conflict. However, after repeated warnings to Russia not to use long-range weapons inside Ukraine and to stop attacking Ukrainian energy grids went unheeded, the White House decided to provide Ukraine with the same capabilities.

An NSC spokesperson said President Biden directed his team to send the ATACMS after North Korea provided Russia with ballistic missiles that have now been used in Ukraine and after Russia has repeatedly attacked civilian infrastructure inside Ukraine. The U.S. has imposed limitations on the use of the long-range systems, including prohibiting their use to strike inside Russia and restricting their use to within sovereign Ukrainian territory, which, according to the U.S. government, includes Crimea.

Defense Secretary Lloyd Austin, testifying before the House Appropriations Subcommittee on Defense last week, warned that without funding for more weapons to Ukraine, Russia is gaining the upper hand. "We're seeing the Ukrainians be challenged in terms of holding the line - they're doing a very good job, a credible job - but in order to continue to do that, they're going to need the right materials, the right munitions, the weapons to be able to do that," Austin said.

Speaking on NBC News' "Meet the Press" on Sunday, Ukrainian President Volodymyr Zelenskyy said the new aid will give the country a chance at "victory" as it defends itself from Russia. "I think this support will really strengthen the armed forces, I pray, and we will have a chance at victory if Ukraine really gets the weapons system, which we need so much, which thousands of soldiers need so much," he said.