El Niño events in '86/87 and '91/92 affected the East Asian monsoon. During El Niño, a southerly wind anomaly near East Asia intensified the summer monsoon in '86/87 but weakened the winter monsoon in '91/92. The impact is linked to changes in convective activities over the western equatorial Pacific, influenced by sea surface temperature anomalies. Historical data supports the relationship between El Niño and the East Asian monsoon, but the same effect is not seen during La Niña periods.