Russia has all the forces it needs on Ukraine's border if it were to decide to carry out an "incursion" into the country and it could achieve its objective in three to five days, NATO's top military commander said on Wednesday.
Calling the situation on the border "incredibly concerning", NATO's Supreme Allied Commander Europe, U.S. Air Force General Philip Breedlove, said NATO had spotted signs of movement by a very small part of the Russian force overnight but no indication that it was returning to barracks.
NATO foreign ministers meeting in Brussels had asked him to draw up by April 15 a package to reassure nervous NATO allies in eastern Europe that would include reinforcements by land, air and sea, he said in an interview with Reuters and The Wall Street Journal.
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.
NATO Secretary-General Anders Fogh Rasmussen said Russia's actions meant there could be no "business as usual".
"So today, we are suspending all practical cooperation with Russia, military and civilian," he told a news conference. German Foreign Minister Frank-Walter Steinmeier said NATO's future relationship with Russia would depend, among other things, on whether Russia started withdrawing troops from the Ukrainian border.
Ministers also ordered military commanders to draw up plans for reinforcing NATO's defenses to shore up confidence among the alliance's Eastern European members, including former Soviet republics in the Baltics, that NATO is ready to defend them.
The measures could include sending NATO soldiers and equipment to Eastern European allies, holding more exercises, ensuring NATO's rapid-reaction force could deploy more quickly, and reviewing NATO's military plans. Military planners will come back with detailed proposals within weeks, a NATO official said.
U.S. Secretary of State John Kerry said NATO's preference was for a de-escalation and diplomatic route out of the crisis.
"At the same time, it is important for everybody in the world to understand the NATO alliance takes seriously this attempt to change borders by use of force," he said.