keep a close watch on

keep (a) close watch on (someone or something)

To monitor someone or something closely. Keep a close watch on this pot so that the soup doesn't boil over.
See also: close, keep, on, watch

keep a close watch on someone or something

to watch someone or something very carefully. Let's keep a close watch on Fred and his friends. I want to keep a close watch on the house across the street.
See also: close, keep, on, watch

keep a close ˈeye/ˈwatch on somebody/something

watch somebody/something carefully: Over the next few months we will keep a close eye on sales.
References in classic literature ?
What we can do is simply to concentrate all our available strength, keep a close watch on the enemy, and obtain reinforcements.
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