NATO Secretary-General Anders Fogh Rasmussen says the alliance is strengthening its military presence on its eastern borders in response to the crisis in Ukraine.
Speaking after a meeting in Brussels of the North Atlantic Council, NATO's main political decision-making body, Rasmussen said the alliance will be making new military deployments by sea, air, and land "within days."
He said there will be "more planes in the air, more ships on the water, more readiness on the land."
Rasmussen didn't reveal operational details or numbers about the new deployments.
But he said there will be more "air policing" in the Baltic region, and that allied ships will be deployed in the Baltic Sea, eastern Mediterranean, and elsewhere if required.
The NATO chief did not mention any naval deployments to the Black Sea. Russia borders the Black Sea, as well as a naval base on Crimea, the Ukrainian territory that was annexed by Moscow in March to international condemnation.
NATO members Bulgaria, Romania, and Turkey also border the Black Sea.
The United States this week said a Russian fighter jet last weekend made several passes near a U.S. warship that was sailing in international waters in the Black Sea.
The new NATO deployments will come in addition to the United States' recent dispatch of fighter jets to Poland and the Baltic states to boost air patrols.
WATCH: Ukrainian troops and local pro-Russia protesters face off in Kramatorsk.
At his news conference, Rasmussen described the new deployments as being about "defense, deterrence, and de-escalation," and said they were "entirely in line" with NATO's international commitments governing the activities of military forces.
The NATO chief also stressed that the military alliance prefers a political solution to the Ukrainian crisis, and said he hoped talks scheduled for April 17 in Geneva would lead to an easing of tensions.
Those talks are planned to bring together officials from the United States, Russia, Ukraine's Western-backed government, and the European Union.
Rasmussen called on Moscow to make clear that Russia "doesn't support the violent actions of well-armed militias or pro-Russian separatists" in eastern Ukraine.
Earlier on April 16, Russian flags were raised above armored vehicles
that were seen traveling in two towns in eastern Ukraine where pro-Russian groups have seized public facilities.
Ukrainian government officials later admitted six armored vehicles had been seized by pro-Russian forces.
NATO says it estimates that Russia has massed some 40,000 troops on Ukraine's eastern border, in preparation for a possible incursion into east Ukraine.
Russia has denied Western charges that it has been orchestrating the unrest in Ukraine in a bid to undermine the Ukrainian government and potentially seize territory.
Shortly after Russia annexed Crimea, NATO suspended most cooperation with Moscow.
Russia responded by withdrawing its military envoy to the alliance.
With reporting by AP, Reuters, and AFP