Stock futures fell early Tuesday as Russia’s Vladimir Putin updated the country’s nuclear doctrine. The changes mean that Russia will now view any attack by a non-nuclear country supported by a nuclear power as a joint attack, Russian news agency TASS reported Tuesday. “Moscow also reserves the right to consider a nuclear response to a conventional weapons attack threatening its sovereignty, a large-scale launch of enemy aircraft, missiles, and drones targeting Russian territory, their crossing of the Russian border, and an attack on its ally Belarus,” TASS added.