NATO Secretary General Anders Fogh Rasmussen announced the agreement to create the force as the Western military alliance wrapped up a two-day summit in the Welsh town of Newport on Friday.

Rasmussen said a command headquarters would be set up in an Eastern Europe, which would house supplies and equipment, and thus enable the "spearhead" force to mobilize swiftly to any attack on NATO territory.

"It sends a clear message to any potential aggressor: Should you even think of attacking one ally, you will be facing the whole alliance," Rasmussen said.

The outgoing NATO boss also said patrol flights over Baltic states as well as other defense measures already in place would be extended indefinitely.

US President Barack Obama also welcomed the decision to create the spearhead force, saying it demonstrated that the alliance was "fully united" behind the government of Ukraine, its territorial integrity, and right to self-defense.

He added that all 28 NATO member states would now be providing Kyiv with security assistance, including non-lethal equipment, fuel and medical care for the country's soldiers.

"This commitment makes clear that NATO will not be complacent, Obama said.

The US president also said that Washington and the European Union were likely to impose new sanctions on Russia, despite the news that a ceasefire agreement had been signed by Ukraine and pro-Russia separatists.

"The only reason that we're seeing this ceasefire at this moment is because of both the sanctions that have already been applied and the threat of further sanctions," he said.

Combating 'IS' militants

Another key concern discussed in Newport was the rise of "Islamic State"(IS) militants, who have taken large swathes of Syria and northern Iraq in recent months.

Following a meeting of ministers from 10 nations on the fringes of the NATO summit, Obama said key allies stood ready to join the US in military action against IS militants in Iraq.

"Key NATO allies stand ready to confront this terrorist threat through military, intelligence and law enforcement as well as diplomatic efforts," Obama said after the talks aimed at forming what US officials have referred to as a "core coalition."

"Already allies have joined us in Iraq where we have stopped ISIL's (IS) advances, we have equipped our Iraqi partners and helped them go on offense," he said.

Chancellor Angela Merkel, though, indicated that while the 10 nations, including Germany, had expressed their determination to stop the IS, not concrete measures had been agreed in Newport.

"These countries that have expressed a willingness, have sensibly agreed to stay in tough and to discuss the next measures with each other," the chancellor said.

pfd/dr (Reuters, AP, AFP, dpa)