Ukrainian President Volodymyr Zelenskyy mentioned the S-300s by name when he spoke to US lawmakers by video Wednesday, appealing for anti-air systems that would allow Ukraine to ``close the skies'' to Russian warplanes and missiles.

Slovak Defense Ministry spokesperson Martina Koval Kakascikova said Slovaks expect the issue to be on the agenda when Austin comes to Bratislava for talks.

Slovakia has no objections to providing its S-300s to Ukraine, she said. ``But we can't get rid of a system that protects our air space if we don't have any replacement.''

The S-300s use long-range missiles that are capable of flying hundreds of miles and knocking down cruise missiles as well as warplanes. The Soviet-era anti-air defense systems could be valuable in thwarting Russian air attacks on cities and other targets.

US President Joe Biden said Wednesday that the US would help provide long-range air defense systems to Ukraine, but gave no details.

US officials had no comment on any S-300 swap.

Three NATO members, Slovakia, Greece, and Bulgaria _ are reported to have S-300s.