Among other things, the crisis has heightened concerns in the United States and in Europe about the future direction and scope of the transatlantic security relationship and the cornerstone of that relationship, the North Atlantic Treaty Organization (NATO). Some policy makers and analysts have called for a reassessment of the transatlantic community's progress in realizing its goal of a Europe "whole, free, and at peace," citing security concerns in some of NATO's Central and Eastern European member states and ongoing territorial disputes in countries on the alliance's borders, such as Moldova, Ukraine, and Georgia. Russia's actions in Ukraine have heightened these concerns. NATO's response to the crisis thus far has focused on demonstrating support for Ukraine and its territorial integrity; reaffirming the allied commitment to defensing Central and Eastern European allies; and rebuking Russia. Despite calls from some member states, NATO has thus far ruled out permanent troop deployments in the region. Although they have welcomed these measures, some allies in Central and Eastern Europe have called for a more robust demonstration of NATO's willingness and capacity to defend them. U.S. Reassurance Measures in Central and Eastern Europe – Operation Atlantic Resolve and the Proposed European Reassurance Initiative

As well as being a key proponent of the NATO response thus far, the Obama Administration has taken additional military measures intended to reassure Central and Eastern European allies. According to the Department of Defense, these and other U.S. troops have participated in at least ten land-based military exercises with NATO Central and Eastern European and other allies this spring and summer. The Defense Department has also enhanced U.S. naval presence in the Black and Baltic Seas. Language issues have caused tensions between Russia and Latvia. On June 4, the Administration announced an additional $5 million in security assistance to Ukraine. Some Members of Congress have called on NATO to offer to purchase the Mistrals built for Russia from France. Prospects for NATO Enlargement

Russian actions in Ukraine have prompted some U.S. observers and Members of Congress to call for a more concerted NATO effort to enlarge the alliance, particularly to the east. Montenegro has had a Membership Action Plan (MAP) since December 2009. Representatives of Ukraine's current government have said the country is not seeking NATO membership. In addition to the aforementioned U.S. military responses to the crisis in Ukraine, they note that the United States was a key proponent of NATO's drafting of contingency plans for the defense of Poland and the Baltic States in 2009, and they draw attention to recent U.S. calls for a new round of NATO contingency planning. While they have welcomed these steps, critics of the Administration's and NATO's response to Russian actions in Ukraine have argued that more should be done to support Ukraine, reassure allies in Central and Eastern Europe, and counter Russian aggression. Some have called for bolstered and possibly permanent NATO and/or U.S. troop deployments in Central and Eastern Europe, as well as more frequent military exercises, including in the Black Sea. As discussed above, the United States has provided the Ukrainian government with some nonlethal military aid but has thus far declined to provide lethal military aid. Some analysts, including a former NATO military commander, have argued that the United States and other allies should consider providing additional military assistance, including intelligence and surveillance capabilities and anti-aircraft and anti-tank weapons. Congress could continue to play an important role in shaping U.S. and NATO responses to Russia's actions in Ukraine.
Russia's actions in Ukraine and its alleged role in the downing of Malaysia Airlines Flight 17 have caused observers and policy makers on both sides of the Atlantic, including Members of Congress, to reassess the role of the United States and the North Atlantic Treaty Organization (NATO) in upholding European security. The security concerns of NATO's Central and Eastern European member states and non-NATO member states such as Moldova and Ukraine are of particular concern.
NATO has strongly condemned Russian actions in Ukraine and has taken steps aimed both at reassuring allies and partners in Central and Eastern Europe and at deterring further Russian aggression. These include demonstrations of support for Ukraine and its territorial integrity; actions to demonstrate NATO's commitment to defending Central and Eastern European allies; and measures aimed at rebuking Russia. NATO members have said they will continue to conduct previously planned military exercises in Ukraine and elsewhere in the region.
The United States has been a key driver of the NATO response and has taken additional military measures intended to reassure its allies and partners in Central and Eastern Europe. These include the deployment of U.S. fighter jets and 600 paratroopers to Poland and the Baltic states, and U.S. naval vessels to the Black and Baltic Seas. In June, the Obama Administration requested congressional approval for $925 million in the Department of Defense's FY2015 Overseas Contingency Operations (OCO) budget to fund a proposed European Reassurance Initiative (ERI). Among other things, the ERI would enable augmented U.S. troop rotations and military infrastructure in Central and Eastern Europe. The United States has supplied the Ukrainian government with some nonlethal military assistance, but has thus far ruled out providing lethal military aid.
Although these actions have been welcomed by supporters of the United States and NATO, some analysts and allied governments have called for a more concerted military response. Among other things, critics have called for more robust forward or permanent deployment of U.S. and NATO forces in Central and Eastern Europe; additional military exercises in the region; and additional military assistance to Ukraine, including military training and anti-tank and anti-aircraft weapons.
The U.S. Congress has played an active role in guiding the U.S. response to the Ukraine crisis, including by authorizing a $1 billion loan guarantee to the Ukrainian government, $150 million in financial assistance to Ukraine and other Central and Eastern European countries, and sanctions against Russia (P.L. 113-95). However, some Members of Congress have called on the Obama Administration and NATO to take additional military action to reassure allies and deter Russia. Some Members have also called for a more resolute demonstration of NATO's commitment to enlargement, including to Georgia, a former republic Soviet republic, with which Russia had a military conflict in 2008. For example, the proposed Forging Peace through Strength in Ukraine and the Transatlantic Alliance Act (H.R. 4433) calls for additional NATO and U.S. military assistance to Ukraine and calls for immediate NATO membership for Montenegro and the granting of a NATO Membership Action Plan (MAP) to Georgia.
This report addresses the NATO and U.S. military response to the crisis in Ukraine. It does not discuss political, economic, or energy policy responses. For information on these and other aspects of the crisis response, see CRS Report RL33460, Ukraine: Current Issues and U.S. Policy, by [author name scrubbed].