The key point about the summit meeting in Moscow between Russian President Putin and German Chancellor Merkel is that it signals Merkel's acceptance that Putin's hold on power is secure.Angela Merkel met Vladimir Putin for the first time in Moscow in 2 years, her last visit there being a brief visit she made in 2015 to commemorate the fiftieth anniversary of Victory In Europe.
Apart from that one meeting, which it was impossible politically for Merkel to avoid, Merkel's visit to Moscow today is her first visit there since her negotiation with Putin in February 2015, which took place in the run-up to the signing of the Minsk Agreement.
Merkel has avoided to Moscow since then, and has signalled her disapproval of visits there by other German politicians.
Merkel's visit to Moscow is supposed to be taking place in the run-up to the G20 summit in July in Germany,which Merkel will be hosting.
This is an excuse than than a reason for the visit. Even if it is true that Merkel is busy contacting G20 leaders in preparation for the summit, that did not require her to go to Moscow to meet Putin there.
Comment: Here it looks like the "North Korea threat" is being used as a pretext for US to gain Japan as an ally against China.