– A reinvigorated NATO flexed old Cold War muscles Tuesday as the Atlantic alliance’s chief recommitted to defending Eastern European and Baltic nations rattled by Russia’s military moves and its annexation of Crimea.

At the opening of a two-day meeting of NATO foreign ministers, Secretary-General Anders Fogh Rasmussen said the alliance has seen no signs of Russian troop withdrawals along the Ukraine border, as Moscow has claimed. A senior U.S. State Department official had called Russia’s promised pullback a “gesture,” but a welcome one.

“We have all challenged the tactics of intimidation,” Secretary of State John Kerry said after meeting Tuesday with NATO members and Ukrainian envoys.

The alliance moved to suspend many military and civilian ties with Russia over its military incursion and annexation of Crimea, but it stopped short of ordering new troop deployments of its own, a move that could provoke a larger confrontation.

“NATO has consistently worked for closer cooperation and trust with Russia” for two decades, the alliance ministers said in a statement. “However, Russia has violated international law” and its agreements with NATO, they said. “It has gravely breached the trust upon which our cooperation must be based.”

Rasmussen did not rule out posting troops in nations at Russia’s front door in the future, something the alliance has largely refrained from doing. NATO could establish permanent bases in front-line allied nations, alliance officials said this week.

Ukraine is not a member of the alliance but cooperates with it, to Russia’s frequent dismay. Ukraine’s foreign minister reiterated Tuesday that his nation is not seeking NATO membership now but is exploring greater cooperation.

NATO foreign ministers agreed Tuesday to intensify the alliance’s partnership with Ukraine and provide additional assets to Eastern European partners.

“Russia’s aggression against Ukraine challenges our vision of a Europe whole, free and at peace,” Rasmussen said. “We are now considering all options to enhance our collective defense, including an update and further development of defense plans, enhanced exercises and also appropriate deployment.”

The United States has joined Black Sea naval exercises, and NATO members have increased air patrols over the Baltic states and employed AWACS surveillance planes over Poland and Romania.

Eastern European leaders have expressed unhappiness with the pace at which NATO has sought to bulk up its presence on the front lines with Russia. Polish Prime Minister Donald Tusk said the results have been “unsatisfactory.”

“We are gaining something step by step, but the pace of NATO increasing its military presence for sure could be faster,” he said.

In Washington, the House considered an aid package for Ukraine, whose new Western-oriented leaders have committed to economic and political reform and elections in May.

The 28-member alliance’s regular spring meeting of foreign ministers was energized by Russia’s move to invade and then annex Crimea from Ukraine, and to deploy as many as 40,000 troops along its border with Ukraine.

NATO, originally formed as a U.S.-backed bulwark against the Soviet Union, has expanded in the past 15 years to include many former Soviet satellite states, often over Russian complaints. NATO sometimes invites Russia to attend sessions, but that was not the case this time.

“We will make clear that Russia’s actions are unacceptable. We will take decisions on which cooperation with Russia is still appropriate,” Rasmussen said. “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.”

“Clearly we have a NATO that is now in the business, in the context of events in and around Ukraine, of rebalancing its mission,” a senior U.S. official said.