"Anderson", operated with "Yorktown" through late April, patrolling the Coral Sea as the sole barrier against Japanese expansion in that region, putting into Tongatapu, in the Tonga (or "Friendly") Islands, late that month. With intelligence data indicating that the postponed movement against Tulagi, in the Solomons, was imminent—confirmed by the Japanese landing men and supplies there on 29 April and establishing a seaplane base on the heels of the retreating Australian garrison, TF 17 moved north to deal with this threat.