To enter Russia for any purpose, a U.S. citizen must possess a valid U.S. passport and a bona fide visa issued by a Russian embassy or consulate. It is impossible to obtain an entry visa upon arrival, so travelers must apply for their visas well in advance. U.S. citizens who apply for Russian visas in third countries where they do not have permission to stay more than 90 days may face considerable delays in visa processing. Travelers who arrive in Russia without an entry visa will not be permitted to enter the country, and face immediate return to the point of embarkation at their own expense.
A Russian entry/exit visa has two dates written in the European style (day/month/year) as opposed to the American style (month/day/year). The first date indicates the earliest day a traveler may enter Russia; the second date indicates the date by which a traveler must leave Russia. A Russian visa is only valid for those exact dates and cannot be extended after the traveler has arrived in the country, except in the case of a medical emergency.
Russian tourist visas are often granted only for the specific dates mentioned in the invitation letter provided by the sponsor. U.S. citizens sometimes receive visas valid for periods as short as four days. Even if the visa is misdated through error of a Russian embassy or consulate, the traveler will still not be allowed into Russia before the visa start date or be allowed to leave after the visa expiration date. Any mistakes in visa dates must be corrected before the traveler enters Russia. Travelers should ensure that their visas reflect intended activities in Russia (e.g., tourism)
Please note that non-U.S. passport holders are responsible for obtaining the required documentation applicable for their entry.