It reads like Keir Starmer wrote it. He has used the phrase paper tiger in reference to Ukraine in the past and Trump just visited and spoke with Starmer.

Here is a speech from 2024 where Starmer uses it:

Because the alternative would be to confirm the worst claims about this place - that international law is merely a paper tiger and that aggressors can do what they will.

https://www.gov.uk/government/news/pm-united-nations-general-assembly-speech-26-september-2024