The pair mimicked theCameron's stern expression in the photos, sending up his rare "action shot" that elicited thousands of retweets from amused users.
"I've been speaking to @BarackObama about the situation in Ukraine. We are united in condemnation of Russia's actions," Cameron wrote, before comedian Delaney chimed in: "@David_Cameron @BarackObama Hi guys, I'm on the line now too. Get me up to speed."
Sir Patrick capped things off, adding that he was "now patched in as well. Sorry for the delay."
Cameron and Obama have shown a united front over the Ukraine crisis, saying that Russia must face "significant costs" if it does not change its course.