The United States announced on Thursday its approval of a $5 billion sale of up to 600 Patriot missiles and related equipment to Germany, which has donated several of the advanced air defense systems to Ukraine.

The proposed sale of the PAC-3 MSE missiles “will support the foreign policy and national security of the United States by improving the security of a NATO ally that is an important force for political and economic stability in Europe,” the Defense Security Cooperation Agency (DSCA) said in a statement.

It “will improve Germany’s capability to meet current and future threats and increase the defensive capabilities of its military. It will support Germany’s goal of improving national and territorial defense as well as interoperability with US and NATO forces,” the statement added.

Under new NATO defense plans, Germany will need to quadruple its air defenses to protect infrastructure and military forces in the event of severe tensions or war, one security source told Reuters last month.

Germany had 36 Patriot air defense units, which launch missiles, when it was NATO’s frontline state during the Cold War. Today, German forces are down to nine Patriot units, after donating three to Ukraine since the Russian invasion in 2022.

The U.S. State Department approved the possible sale of the missiles, and the DSCA on Thursday provided the required notification to Congress, which still needs to sign off on the transaction.

Ukraine has faced repeated Russian missile barrages and drone attacks targeting its infrastructure, leaving it in desperate need of additional air defenses.

After the outbreak of the Ukraine war, Berlin dropped its traditionally pacifist stance and has become Kyiv’s second-biggest supplier of military aid, after Washington.