Why is there so much worry about the rising inflation in the US? Will the RBI have to worry more about US inflation than about India inflation?

Now, that may be stretching things a bit too far, but you are right that the recent spike in US inflation to 4.2% has left the RBI worried. We will come back to that later. Indian inflation fell from 5.52% to 4.29% in April 2021 led by lower food inflation and lower core inflation. That is good but there is still too much of base effect in that. Also, low inflation in rural areas could be an out come of weak demand due to COVID spreading rapidly in the hinterland.

US inflation came in at 4.2% and was much higher that estimates. But bond yields had apparently got a whiff well in advance. The bet is that with such high rates of inflation, the Fed may front-end rate hikes. If that happens, it could pose a big problem for the RBI. India has limited influence on US inflation. However, a spike in Fed rates would make US bonds more attractive in risk-adjusted terms. The result could be FPI debt outflows.

To answer your question, while RBI may not obsess with US inflation, it is surely worried by US inflation at 4.2%. A lot will now depend on the FOMC minutes and Fed policy response.