The U.K. on Wednesday expelled a Russian diplomat in retaliation for Moscow’s recent expulsion of a British official and the smear campaign that followed. Britain’s Foreign, Commonwealth and Development Office said it summoned the Russian ambassador to its offices in London to inform him of the “reciprocal action.” The tit-for tat moves reflect spiraling tensions between Moscow and the West. “This behavior is wholly unacceptable, and we will not tolerate harassment or intimidation of our diplomatic staff,’’ the Foreign Office said in a statement. The move came after Russia last month expelled a British diplomat over spying allegations that the U.K. rejected as “complete nonsense.” Russia’s top domestic security and counterintelligence agency, the Federal Security Service, known as the FSB, said the British diplomat had sought to gather “sensitive information” about the Russian economy in “unofficial meetings” with Russian experts. The diplomat was ordered to leave Russia within two weeks.…