AWS Athena Iceberg Multiple Row UPDATE

I am trying to update an iceberg table on Athena joined with another table

My script:

UPDATE sampledb.icbg_tenure_20220905 a INNER JOIN sampledb.cit_update b ON a.msisdn_hash = b.msisdn_hash SET a.activation_date = b.activationdate

Getting error message:

line 1:38: mismatched input 'a'. Expecting: '.', 'SET'

Update iceberg table on athena joined with another table