Ukrinform repots this with reference to Reuters.
It is noted that the MiG jets, relocated to Kaliningrad region, would on round-the-clock duty.
Kinzhal is a Russian hypersonic ballistic missile. After being put into service in 2018, only a few dozen of them were produced. The Kinzhal missile, which is launched from the air, can reach speeds of up to 12,000 km/h, making it a difficult target for interception by air defense systems.