NATO defense ministers decided Thursday to significantly boost the size of the alliance’s rapid-reaction force to deal with growing threats such as the war in Ukraine and Islamic radicalism along its southern flank.

“In Ukraine, violence is getting worse and the crisis is deepening. Russia continues to disregard international rules and to support the separatists,” Secretary-General Jens Stoltenberg said. “In North Africa and the Middle East, violent extremism is spreading, (fueling) terrorism in our own countries.”

Outgoing Defense Secretary Chuck Hagel warned that those divergent concerns could cause a split in the alliance.

“I worry about the potential for division between our northern and southern allies,” he said. He added that this was a time for unity and that the alliance would have to address all challenges at the same time.

Stoltenberg said the alliance’s 28 ministers had agreed to increase the NATO Reaction Force to about 30,000 troops — more than double its originally planned strength of 13,000.

He said ministers had also agreed on the composition of a brigade-strength Spearhead Force, whose lead elements would be ready to move into trouble spots within 48 hours of being activated. France, Germany, Italy, Poland, Spain and Britain had offered to provide the main elements of that force.

“This is a strong signal of NATO solidarity. And it shows that European allies are fully playing their part, taking the lead in protecting Europe,” Stoltenberg said at the end of the one-day meeting at NATO headquarters in Brussels.

The allies decided to immediately establish six multinational command and control centers in eastern Europe. These will be located in Bulgaria, Estonia, Latvia, Lithuania, Poland and Romania. The centers will be comprised of up to 50 staff officers, half of them from the home nation, officials said.

“If a crisis arises, they will ensure that national and NATO forces from across the Alliance are able to act as one from the start. They will make rapid deployment easier,” Stoltenberg said.

“This is the biggest reinforcement of collective defense since the Cold War,” he declared.

The NATO meeting came amid a flurry of diplomatic activity on Ukraine.

U.S. Secretary of State John Kerry met with Ukrainian President Petro Poroshenko in Kiev on Thursday. In a surprise peace initiative, German Chancellor Angela Merkel and French President Francois Hollande were set to meet with Poroshenko on Thursday and with Russian leader Vladimir Putin in Moscow on Friday.

“We know there are now new initiatives undertaken by Hollande and Merkel, and we support those initiatives and we hope they will lead to concrete results,” Stoltenberg said.

The defense ministers’ meeting on Thursday was the first since NATO heads of state convened in September and decided to bolster the alliance’s defenses in eastern Europe in response to Russia’s annexation of Ukraine’s Crimea peninsula.

The nearly yearlong crisis has re-energized the Cold War alliance, which had been searching for a raison d’etre since the scaling back of the war in Afghanistan. At the end of last year, NATO announced it was ending combat operations in Afghanistan. But the alliance still maintains thousands of advisers and other troops in the country to help the Afghan army and police, who face threats from the Taliban and other insurgent groups.

In the meantime, NATO has established a more robust presence in Poland and the Baltic states, which lie on Russia’s periphery. The United States has taken a lead role in the rotational presence and training in those states.

Hagel said that in its initial phase, the 66-year-old alliance focused on defending its members from Soviet aggression; after 1990, it adapted to the collapse of communism and the end of the East-West divide by conducting out-of-area operations in the Balkans, Afghanistan, Libya and elsewhere. “Now, in its third phase, the alliance must be prepared to address all these challenges at once,” Hagel said.

Stoltenberg is scheduled to meet with Russian Foreign Minister Sergey Lavrov at the annual Munich Security Conference, which opens Friday. Although NATO suspended all practical cooperation with Russia last year, the alliance has kept channels open for political contacts.

lekic.slobodan@stripes.com