President Trump woke up Wednesday morning and warned Russia to get ready for the missiles he is planning to launch into Syria, suggesting that the American rockets would evade Russian air defenses because they’re “nice and new and ‘smart.’ ”

“Russia vows to shoot down any and all missiles fired at Syria,” Trump tweeted. “Get ready Russia, because they will be coming, nice and new and ‘smart!’ You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!”

Trump has been signaling that he is planning a military response to Syrian President Bashar al-Assad’s suspected use of chemical weapons in an attack Saturday on the town of Douma outside Damascus. The president previously criticized the Obama administration for telegraphing its military moves in advance.

When Trump says “smart” missiles, he means missiles that use precision guidance systems based on lasers or satellite-powered GPS to pinpoint and strike targets with exactitude.

The U.S. military has been using so many precision-guided munitions in the fight against the Islamic State in recent years that the Pentagon had to work with defense contractors to step up the weapons’ production and introduce new types of missiles to the fight. The military can also fasten “smart” guidance kits on existing “dumb” bombs and rockets to outfit them with the capability to hit specific targets.

The Pentagon has long criticized Russia for using “dumb bombs,” or weapons that lack precision-guidance technology, while striking targets in Syria. Missiles without precision guidance are far cheaper and in large supply in Russia’s arsenal but have a poorer track record of hitting specific targets, and therefore cause more collateral damage.

Former defense secretary Ash Carter, speaking in Senate testimony in late 2015, said at the time that the vast majority of Russia’s strikes in Syria, about 85 percent to 90 percent, “use dumb bombs, which obviously increases the possibility of civilian casualties.”

Trump launched 59 Tomahawk cruise missiles at a Syrian military airfield in April 2017 in retaliation for a chemical attack. The military action marked the first direct U.S. assault on Assad’s government. The Pentagon otherwise has limited its involvement in Syria to defeating the Islamic State primarily through local proxy forces. The United States warned Russia before the strike last year.

Tomahawk cruise missiles, first used by the U.S. military during Operation Desert Storm, maneuver easily and fly low to hit targets. They can be reprogrammed midflight to hit different GPS coordinates.