Russia began deployment of the EKS/Kupol space-based segment of its early-warning system in 2015, with a launch of Cosmos-2510 on 17 November 2015. That was the first of six Tundra launches - Cosmos-2518 in May 2017, Cosmos-2541 in September 2019, Cosmos-2546 in May 2020, Cosmos-2552 in November 2021, and Cosmos-2563 in November 2022. It appeared that the Air and Space Forces would launch one satellite annually, but I don't see a launch in 2023.

The first two satellites worked for about five years. Their station-keeping maneuvered ended in late 2020 and late 2021 respectively. This leaves the system with four operational satellites. Although the full system is supposed to include ten satellites, I believe that four can provide sufficient coverage. They appear to have true look-down capability, adequately covering everything north of the equator. Since the satellites are deployed on highly elliptical orbits, they replace each other at the apogee, so there is probably at least one satellite that is in a position to see a launch.

The system does not need ten to provide continuous coverage. Rather, the idea is to have more than one satellite looking at each point. That helps reduce false positives. Ideally one would need three to almost completely eliminate them, but it's not absolutely necessary. Having one means that operators should be on guard regarding false positives, and since they know the capability of the system, they probably are. It is also worth keeping in mind that the role of space-based early warning in Russia is quite different from that in the US. As I explained elsewhere, it's a matter of geography. So, even if there were no satellites at all, the basic function of the early-warning system would not change dramatically.

If Russia keeps the current deployment rate, about one satellite a year, and assuming that the service life stays at five years, getting to a full constellation of ten will be a challenge. Something will have to change.

At some point there was a talk about a geostationary early-warning satellite, but we haven't heard anything about it for quite some time.