In June, the United States started supplying Ukraine with high mobility artillery rocket system launchers, also called HIMARS. From the moment they hit the battlefield, HIMARS made a huge impact in how the war was being fought.

This week, however, the Pentagon revealed the U.S. secretly modified the HIMARS given to Ukraine. According to the Wall Street Journal, the U.S. configured the launchers to make sure they could not fire long-range missiles into Russia.

The U.S. supplied Ukraine with 20 HIMARS this summer, and a large inventory of satellite-guided rockets with a 50-mile range. Without the HIMARS, Ukraine likely would not have been able to hold off Russia for this long, let alone launch successful counteroffensives.

Russian Foreign Ministry spokeswoman Maria Zakharova said in September that the U.S. would be crossing a red line if it gives long-range missiles to Ukraine. The Biden administration said if Ukraine were to use U.S. made weapons to launch strikes within Russia, the risk of a wider war with Moscow would grow.

Instead of waiting on the U.S. or the West for long-range weaponry, though, it looks like Ukraine may have just created its own ability to launch long-range attacks against Russia.

On Tuesday, Russian state media released video of what it said was the aftermath of a drone strike on the Kursk Airfield. Two other Russian air bases were hit Monday in similar fashion. Russia said the weapons used were Soviet-era jet drones, and essentially operate like cruise missiles. Ukrainian special forces close to the bases reportedly helped guide the drones to their targets.

While Ukraine didn’t formally claim responsibility for the attack within Russian territory, which is normal, the fact that Ukraine now appears to have the ability to launch strikes deep within Russia marks a new chapter in the 9-month-old war.