Alexinsky joined Lenin in Geneva, but fell out with him and in 1909 joined the ultra left Vpered, group, led by Alexander Bogdanov. On the outbreak of war, he veered sharply to the right, becoming an outspoken supporter of the Russian war effort. Leon Trotsky, who described Alexinsky as a "shrieking orator and passionate lover of intrigue" alleged that he made a practice of accusing opponents of the war of being paid German agents, and was expelled from the Paris Association of Foreign Journalists as a "dishonest slanderer". He returned to Russia in 1917, after the February revolution, and in July produced documents to support his contention that Lenin was a German agent. After the October Revolution he arrested by the Cheka but was released on bail.