President Joe Biden announced that the U.S. would impose harsh sanctions against Russia in the wake of the country’s invasion of Ukraine just hours prior.

“Today I’m authorizing additional strong sanctions and new limitations on what can be exported to Russia,” Biden said in a speech on Thursday afternoon. “This is going to impose a severe cost on the Russian economy, both immediately and over time. We have purposely designed these sanctions to maximize the long-term impact on Russia and minimize the impact on the United States and our allies.”

Biden added that a coalition of countries representing more than half of the global economy, including 27 members of the European Union, are amplifying the international response against Russia.

“We will limit Russia’s ability to do business in dollars, euros, pounds and yen,” Biden said. We are going to stunt the ability to finance and grow the Russian military. We’re going to impair their ability to compete in a high-tech, 21st-century economy. We’ve already seen the impact of Russia’s currency in the ruble, which early today hit its weakest level ever in history.”

Biden said NATO members will meet at a summit on Friday to map out the next steps of the global alliance’s stance against Russia. He also said U.S. forces will defend NATO allies “with the full force of American power.”

“Our forces are not, and will not, be engaged in the conflict with Russia in Ukraine,” Biden said. “Our forces are not going to Europe to fight in Ukraine, but to defend our NATO allies and reassure those allies in the east. As I made crystal clear, the United States will defend every inch of NATO territory with the full force of American power.”

Prior to his address, Biden met with the U.S. National Security Council and leaders from Canada, France, Germany, Italy, Japan and the U.K., many of whom similarly condemned the invasion of Ukraine. The global leaders discussed Russia’s escalating attacks, and Biden also said he spoke overnight with Ukrainian President Volodymyr Zelensky.

After months of escalation, the invasion by Russian forces began before dawn on Thursday, following a TV address from Russian President Vladimir Putin in Moscow. Minutes later, explosions were heard in several towns across Ukraine, including the capital Kyiv.

In a Wednesday night statement, Biden condemned Russia for its “unprovoked and unjustified attack” and said Putin was choosing “a premeditated war that will bring a catastrophic loss of life and human suffering.”

“Russia alone is responsible for the death and destruction this attack will bring, and the United States and its allies and partners will respond in a united and decisive way,” he said. “The world will hold Russia accountable.”