Story highlights Trump and Khan have spent the last year sniping at one another

Khan has charged that Trump is bigoted

Washington (CNN) President Donald Trump's decision to knock London Mayor Sadiq Khan on Monday didn't come out of nowhere.

Trump and Khan have spent the last year sniping at one another, largely over Trump's proposed travel ban that would temporarily bar some Muslims from entering the United States. Trump has used the policy, stalled now in US courts, as an example of the sort of toughness that he says Khan refuses to show amid terrorism attacks that are riling the United Kingdom.

Khan has pushed back, calling Trump bigoted and saying that he doesn't need advice from the US President.

Here's how we got here:

December 7, 2015

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