By Adrian Croft
BRUSSELS, April 1 (Reuters) - NATO suspended all practical cooperation with Russia on Tuesday in protest at its annexation of Crimea and ordered military planners to draft measures to strengthen its defenses and reassure nervous eastern European countries.
Foreign ministers from the 28-nation, U.S.-led alliance were meeting for the first time since the Russian occupation of Ukraine's Crimea region touched off the worst East-West crisis since the Cold War.
They agreed to "suspend all practical civilian and military cooperation between NATO and Russia".
NATO officials said the decision could affect cooperation with Russia on Afghanistan in areas such as training counter-narcotics personnel, maintenance of Afghan air force helicopters and a transit route out of the war-torn country.
Contacts between NATO and Russia at ambassadorial level or higher can continue so they can discuss ways out of the crisis.
Calling Russia's actions in Ukraine unacceptable, NATO Secretary General Anders Fogh Rasmussen said: "Through its actions, Russia has undermined the principles on which our partnership is built, and has breached its own international commitments. So we cannot go on doing business as usual."
Ministers ordered military planners to "develop as a matter of urgency a series of additional measures to reinforce NATO's collective defenses", a NATO official said.
The measures could include sending NATO soldiers and equipment to NATO allies in eastern Europe, holding more exercises, taking steps to ensure NATO's rapid reaction force could deploy more quickly, and a review of NATO's military plans. Military planners will come back with detailed proposals within weeks, the alliance official said.
NATO and Ukraine agreed at a separate meeting of their foreign ministers to step up cooperation and to encourage defence reforms in Ukraine through training and other programmes. NATO allies will send more experts to Kiev.
NATO said there was no sign of a partial withdrawal of Russia's troops from the Ukrainian border, as Moscow had announced on Monday. "Unfortunately, I cannot confirm that Russia is withdrawing its troops. This is not what we are seeing," Rasmussen told reporters.
As NATO ministers convened, Russia warned Ukraine against integration with NATO, saying Kiev's previous attempts to move closer to the defence alliance had had unwelcome consequences.
Ukrainian Prime Minister Arseny Yatseniuk has said the country's new pro-Western leadership is not seeking membership of the Western alliance. However, NATO is expected to step up cooperation with Ukraine's armed forces by training officers, holding joint exercises and promoting reforms.
The United States and its allies have made clear they have no military plans to defend Ukraine, which is not a NATO member, but they have assured allies in eastern Europe, which joined NATO in the last 15 years after the collapse of the Soviet Union that once dominated them, that they will be protected.
Diplomats said earlier that the NATO ministers would consider options ranging from stepped-up military exercises and temporarily sending more forces to eastern member states to the permanent basing of alliance forces in those countries - a step that Moscow would view as provocative.
The United States and other NATO allies have already responded to the crisis by offering more planes to take part in regular NATO air patrols over the Baltic States, which were once Soviet republics. The United States has beefed up a previously planned training exercise with the Polish air force.
In another sign of NATO support, Romanian President Traian Basescu said the United States has asked to boost the number of troops and aircraft it has stationed at an air base in his country, which has a border with Ukraine.
NATO allies differ on how aggressively they should ramp up forces in eastern Europe in response to Russia's actions with eastern European states keen for more NATO support while Western European countries, further away from Russia, are wary of antagonizing Moscow.
Prime Minister Donald Tusk said on Tuesday that the pace at which NATO was increasing its military presence in Poland was unsatisfactory.
Polish Foreign Minister Radoslaw Sikorski, who said earlier he would be satisfied if NATO located two heavy brigades in Poland, said on arrival at the NATO meeting that he would welcome any NATO forces being stationed there. (Additional reporting by Sabine Siebold, Justyna Pawlak and Lesley Wroughton in Brussels, Jeff Mason, Steve Holland and Phil Stewart in Washington, Editing by Mark Heinrich)