Kim Hjelmgaard, and Gregory Korte

USA TODAY

WARSAW — A halt to a decline in defense spending by NATO nations was praised by President Obama here Saturday, although he cautioned that many members of the military alliance still need to pay more to meet their commitments.

Obama said that the alliance had stopped the decline in military spending, but noted that only five of the 28 NATO members — the United States, the United Kingdom, Poland, Greece and Estonia — spend the required 2% of their GDP output on the military.

“For those of you doing the math, that means the majority of allies are still not meeting that 2% mark, a commitment we all made in Wales,” he said. Obama spoke as NATO's two-day summit in Warsaw drew to a close. The last summit was in Wales in 2014.

Obama announced Friday that the U.S. would rotate a battalion of about 1,000 troops into Poland beginning next year. Other NATO allies made similar commitments to send troops to Estonia, Latvia and Lithuania. That’s in addition to previously announced U.S. investments in radar and missile defenses.

Those moves are a direct response to Russia's 2014 annexation of Crimea from Ukraine and other provocations, including support for Ukrainian separatists and the close-call fly-bys of a U.S. destroyer in the Black Sea.

"Russia’s aggressive actions, including provocative military activities in the periphery of NATO territory and its demonstrated willingness to attain political goals by the threat and use of force, are a source of regional instability, fundamentally challenge the alliance, have damaged Euro-Atlantic security, and threaten our long-standing goal of a Europe whole, free, and at peace," NATO said in a summit communique.

Obama called the troop movements to Poland and the Baltic States “the most significant reinforcement of our collective defense of any time since the Cold War.”

He said the increase in spending sent a clear message that NATO was prepared to defend its allies and that it was as "strong" and "nimble" as ever.

The expansion marked the first collective increase in the organization's spending since 2009. Since the last NATO summit in Wales, a majority of NATO members have now halted or reversed declines in defense spending in real terms. In addition to the five members of the bloc that meet the 2% spending requirement, 10 members spend more than 20% of their defense budgets on major equipment, NATO said.

In message to Russia, U.S. will send 1,000 rotating troops to Poland

But Russia wasn't the only focus of the two-day summit.

"The alliance faces a range of security challenges and threats that originate both from the east and from the south; from state and non-state actors; from military forces and from terrorist, cyber, or hybrid attacks" the NATO communique said. "Our security is also deeply affected by the security situation in the Middle East and North Africa,"

Despite pledges, some NATO members still falling behind on defense spending