The Russians are acting like Russians:

TU-95

Two Russian military planes on Friday violated South Korea’s air defense identification zone (KADIZ) four times and flew away following warnings, Seoul’s Joint Chiefs of Staff (JCS) said.

The JCS said that the aircraft first entered the KADIZ north of the eastern island of Ulleungdo at 2:08 p.m. and flew out of it 74 kilometers southeast of Pohang at 2:35 p.m. They re-entered the KADIZ at 3:21 p.m. from the east and then left from the northwest of Jeju Island at 3:45 p.m.

At 4:08 p.m., the planes entered the KADIZ northwest of Jeju and flew out of it at 4:32 p.m. At 5:36, they re-entered the KADIZ from the east of the Dokdo islets and left at 5:53 p.m.

South Korea deployed its aircraft to send warnings to the planes, the JCS explained.  [Yonhap]

You can read more at the link, but the Russians do these flights through US and Japanese ADIZ’s as well likely to assess the response times of ground alert aircraft.