Moscow said on Monday that Western deliveries of longer-range arms to Kyiv would make Russia push Ukrainian forces further back from its borders, essentially increasing the potential territorial losses for Ukraine in the invasion.
The United States has ruled out sending its own or NATO forces to Ukraine but Washington and Britain have agreed to supply precision missile systems which have significantly longer ranges than previous weapons they delivered.
Washington is supplying Ukraine with M142 High Mobility Artillery Rocket Systems, or HIMARS, and Britain will supply M270 multiple-launch systems.
"The longer the range of the systems that will be delivered, the further we will move back the Nazis from that line from which threats to Russian-speakers and the Russian Federation may come," Foreign Minister Sergei Lavrov told a news conference.
Since the start of its invasion, which it calls a "special military operation", Russia has repeatedly said it aims to clear Ukraine of "Nazis". Kyiv and its Western backers say such claims are fiction and that Ukraine is fighting for its survival against an imperial-style land grab.
President Vladimir Putin warned the United States in an interview broadcast on Sunday that Russia would strike new targets if the West supplied longer-range missiles to Ukraine for use in high-precision mobile rocket systems.
The range of the missile systems depends on the munitions used in them. HIMARS systems have a maximum range of 300 km (185 miles) or more but the missiles supplied by the United States have a range of just over 40 miles (64 km) - double the range of the howitzers it supplied.
