KEFLAVIK, ICELAND — Arctic security and Russia's invasion in Ukraine were top of mind as Prime Minister Justin Trudeau arrived in Iceland Sunday for a two-day summit with Nordic leaders. Trudeau is a guest at the annual meeting of leaders from Iceland, Norway, Sweden, Finland and Denmark, where global security was already high on the agenda before 24 hours of chaos in Russia threw even more uncertainty into the mix. Yevgeny Prigozhin, the chief of the mercenary Wagner Group that has been helping the Russian military invade Ukraine, led a brief armed rebellion through several Russian cities Saturday. He got…