By Steve Holland, Matt Spetalnick and Daphne Psaledakis WASHINGTON (Reuters) – The United States on Thursday imposed sanctions against Russian oligarchs as it targeted Russia’s super-rich and others close to President Vladimir Putin, further ratcheting up financial pressure over Moscow’s invasion of Ukraine. The United States imposed full blocking sanctions on eight oligarchs and officials, including Russian tycoon Alisher Usmanov, taking aim at those who have amassed fortunes and political influence through their connections to Putin. “We want him (Putin) to feel the squeeze, we want the peop…