On 2026-06-16 20:21 UTC, RUMETEOR 2-4 and USDMSP 5D-3 F16 (USA 172) reached a closest approach (TCA) of 8.43 km, with a relative velocity of 6.96 km/s. This is a cross-border encounter between objects operated by different nations, the kind of event closely watched for space-security implications. Miss distance and time of closest approach are computed by propagating the latest published orbital elements (TLEs) for both objects. Values update as new element sets are published. Learn more on the Satellite Maneuver Tracker, and see space situational awareness for context.