The State Department booked 19 rooms at the Trump International Hotel Tower in Vancouver at a cost of more than $15,000 during the grand opening of the complex in February that was attended by the Trump children, per a FOIA request by The Washington Post.
The reason: The documents obtained showing the expenditure were highly redacted, but State told WaPo that generally "[e]mbassy and consulate personnel work with the Secret Service to provide assistance on security matters as necessary for conditions in the particular host country."
Worth noting: The Trump hotel in Vancouver isn't actually owned by The Trump Organization — it simply got its name and branding via a management and licensing deal, and Trump earns royalties from the arrangement.