Valmiki Ramayana Yuddha Kanda Sarga 3 Shloka 30

येनकेनतु: by whatever means , मार्गेण: passage, वरुणालयम्: the ocean, abode of Varuna, तराम: cross over , वानरैः vanaras, लङ्कानगरी: Lanka city, हताइति: has destroyed, अवधार्यताम्: taken as destroyed

"If by whatever means the passage of ocean can be crossed by vanaras it can be taken for granted that the city of Lanka is destroyed."