This report describes the economic, military, diplomatic, and domestic resilience tools available to the United States in the event of a Russian invasion of Ukraine. It is important to understand how Russia might invade Ukraine, how specific political goals might influence the invasion plan, what challenges an invasion might face, and what options the US and its European partners should take. U.S. and Ukrainian officials say there is a widespread expectation that any Russian incursion could be carried out at the same time as an offensive cyberattack on Ukraine. A similar Russian military build-up in the spring did not lead to an invasion, although lawmakers and officials say they are now more worried, citing US intelligence that has not been made public. The UK government said a Russian troop buildup on the border with Ukraine since January has increased the threat of military action. Now Ukraine claims that about 90,000 Russian troops are massed near the border. The crisis has evolved and escalated, with new signs of Russian aggression emerging recently, from cyberattacks on Ukrainian government websites to the deployment of Russian troops to neighboring Belarus for joint military exercises. Russia illegally annexed Crimea in 2014 and used protests in Donbass, eastern Ukraine, eastern Ukraine to support and arm pro-Russian separatists. Since Moscow annexed Crimea in 2014, Russian hackers are said to have repeatedly disrupted critical infrastructure in Ukraine, including blackouts in parts of Ukraine in 2015 and 2016. The Russian Foreign Ministry said Western countries used the media to spread false information that Russia might have plans to invade Ukraine. Foreign Minister Sergei Lavrov on February 12 accused America and its allies of conducting a "propaganda campaign against Russian aggression against Ukraine." Russian President Vladimir Putin has denied any aggressive motives, insisting that he is responding to increased NATO activity along his borders and the strengthening of the Ukrainian military. State-sponsored propaganda ranges from late-night attacks on Ukraine on Russian television to a recent article by former Russian President Dmitry Medvedev. Since then, Putin's rhetoric against Ukraine as a tool of Russia's enemies has been taken up and reinforced by the Russian bureaucracy. Putin has used a similar narrative to justify Putin's support for separatists in southeastern Ukraine, another region with large numbers of ethnic and Russian-speaking Russians. People say one of the problems is that Russian President Putin is now worried that Russia could lose Ukraine forever. Putin and other Russian leaders seem to remain genuinely concerned about the possibility of Ukraine eventually joining NATO, even as Western leaders such as US President Joe Biden have spoken out in schools about it. President Joe Biden also suggested that Americans leave Ukraine now, and State Department officials said they might not be able to help Americans still in Ukraine if Moscow invades. US Secretary of State Anthony Blinken suggested that Russia could set a trap for Ukraine to deliberately provoke an invasion of Russia. As Russian troops gather around Ukraine's borders, the unresolved question remains whether Russian President Putin is prepared to bear the domestic and international costs of a full-scale invasion, or whether he will stop pressuring NATO and the West for political concessions. The best way to prevent a full-scale invasion of Ukraine could be the increase in military spending that Russian President Vladimir Putin could face if he decides to roll the dice and launch a major new offensive. Putin has a powerful military option as Putin is amassing 150,000 troops on Ukraine's southern border. Putin could invade Ukraine with overwhelming force to carve up another piece of Ukrainian territory . Putin can use assassinations, disinformation and little green men to bring down Ukraine's democratically elected government. British Defense Secretary Ben Wallace said Russian troops stationed near Ukraine offered Russia several options, including launching an invasion. British Defense Secretary Ben Wallace said he had received assurances from the Kremlin that an invasion was not planned, but with 130,000 Russian troops along the border with Ukraine, those assurances would be judged by Russia's actions. Sullivan said it is unclear whether his Russian counterpart Vladimir Putin has finally given the order to launch an invasion. Officials say there is a distinction between several potential scenarios, whether it is a targeted attack by Moscow on Ukraine or the Kremlin is preparing for a full-scale invasion of Ukraine to overthrow the Ukrainian government. There are many scenarios that trace a Russian invasion, from sending troops into the Donbas region, to conquering strategic regions and blocking Ukraine's access to waterways, to all-out war with Russia advancing on Kiev in an attempt to retake the entire country. A full-scale invasion of southern Ukraine brings with it another potential cost for Russia; namely, a possible wake-up call for a weakened NATO to take the Russian threat seriously. Western powers have repeatedly warned Russia of further aggressive action against Russia, deny it is planning an attack, and argue that NATO support for Ukraine, including increased arms shipments and military training, is a growing threat on Russia's western flank. The picture is complex - - but here's a breakdown of what we know. The US and NATO have described troop movements and concentrations in and around Ukraine as "unusual". Putin has repeatedly described the United States and NATO as Russia's main security threat to its domestic audience, including spreading disinformation that the West is behind the real chaos in Ukraine. Putin is known to refer to southeastern Ukraine as Novorossiya , a term that dates back to the Russian Empire in the 18th century.