Defense Secretary Mark Esper told reporters Saturday night that all of the nearly 1,000 U.S. troops leaving Syria will continue the fight against the Islamic State, or ISIS, from western Iraq, the Wall Street Journal reports.

Why it matters: President Trump has faced scathing criticism from Republicans and Democrats alike for his decision to withdraw U.S. troops from northern Syria, which paved the way for Turkey to lead a military offensive against Kurdish forces who allied with the U.S. in the fight against ISIS.

On Wednesday, the House voted 354-60 condemn Trump's Syria decision.

What he's saying: Esper told reporters traveling with him to the Middle East that U.S. troops would "help defend Iraq" and that the troop movement would be completed in "weeks not days," per Reuters. He didn't rule out U.S. counterterrorism operations being launched from Iraq into Syria, according to AP.

The big picture: Turkey agreed on Thursday to cease its military operation in northern Syria for five days so Kurdish-led Syrian Democratic Forces could withdraw from the area. Kurdish fighters say Turkey has violated the ceasefire, but Esper said it's "generally holding," Reuters reports.

Senate Majority Leader Mitch McConnell (R-Ky.) said in a Washington Post op-ed on Friday Trump's Syria decision would set back years of fighting ISIS and other terrorists and allow Iran and Russia to expand their influence in the area.

Senior Democrats said they walked out of a meeting with Trump Wednesday after he attacked Speaker Nancy Pelosi (D-Calif.) and suggested there was no plan to contain ISIS in Syria. Trump said Pelosi had a meltdown, not him — as Democrats had suggested.

Go deeper:

Editor's note: This article has been updated with new details throughout.