US Defense Secretary James Mattis today outlined a new vision for the Pentagon that seeks to counter Iran and other nations that the United States accuses of pursuing a world order aligned with authoritarian values.

The new National Defense Strategy envisions America’s military focusing on combating authoritarian ideals rather than the protracted global war on terror. The announcement comes as the Donald Trump administration has made clear in recent days that it plans to keep 2,000 US troops in Syria indefinitely to help usher in a political process to replace President Bashar al-Assad and confront Iranian influence in the country.

“To those who would threaten America’s experiment in democracy: If you challenge us, it will be your longest and worst day,” Mattis said in a speech at Johns Hopkins University. “We will continue to prosecute the campaign against terrorists, but great power competition — not terrorism — is now the primary focus of US national security.”

In broad terms, the blueprint lays out a three-pronged approach for America’s military to deal with the looming threat from Iran, which the administration has already framed as the primary competitor to US interests in the Middle East in Trump’s National Security Strategy released last month. Mattis said he aims to build a more lethal force, strengthen alliances and reform the Defense Department’s business practices to help the United States keep up with Russia and China as they continue to beef up their military might.