KIEV, Ukraine (CNN) -

NATO members meeting this week in Wales are expected to create "a very high-readiness force" to deal with Russian aggression in Ukraine and other international conflicts, NATO Secretary General Anders Fogh Rasmussen said Monday.

In a speech on the NATO website, Rasmussen said the fighting force will be part of an overall Readiness Action Plan that "responds to Russia's aggressive behavior -- but it equips the alliance to respond to all security challenges, wherever they may arise."

He said this "spearhead" force would be able to "travel light, but strike hard if needed."

NATO will look at possible upgrades to infrastructure that could include airfields and ports, he said.

The White House supports the idea of a rapid response teams for NATO, but National Security Spokesman Caitlin Hayden cautioned that the force would be "defensive" in posture.

The new force is "not intended as a provocation, or as a threat to Russia, but rather as a demonstration of NATO's continued commitment to our collective defense," Hayden said.

New bases will be set up and equipment pre-positioned at bases, a NATO diplomatic source said.

"We are also facing crises to the southeast and south," said a senior NATO official. The plan "needs to be able to deal with all crises that we might be facing in the future from wherever they might come."

Rasmussen said President Petro Poroshenko of Ukraine will attend the summit and NATO will "make clear our support for Ukraine."

On the ground, Ukrainian forces appear to be outgunned by Russian rebels.

"We have seen as recently as Saturday, that the Ukrainian army is very, very unarmed compared to the rebels," said Michael Bociurkiw, a spokesman for the Organization for Security and Cooperation in Europe, which is monitoring the situation in Eastern Ukraine.

On Monday, U.K. Prime Minister David Cameron told Parliament that the presence of Russian soldiers on Ukraine soil is completely unjustified and unacceptable.

"Russia appears to be trying to force to Ukraine to abandon its democratic choices through the barrel of a gun," he said.

Cameron said new sanctions measures will be drawn up by the EU within a week.

Ukraine airfield attack reported

A Russian army tank attacked airfields in eastern Ukraine on Monday, Ukrainian military officials said, amid worsening tensions between Kiev and Moscow.

A battle is under way at the airport of the eastern city of Luhansk, Ukrainian counter terrorism officials said.

"There is a very, very bad situation developing in Luansk," Bociurkiw said. "Ukrainian officials are warning of a humanitarian catastrophe due to the lack of water and electricity."

Shortly before the attack, Russia urged the Ukrainian military to retreat from civilian locations in the east, saying pro-Moscow separatists in the region will not disarm for fear of getting killed.

The same day, Ukraine said one of its patrol boats was capsized and two of its crew are missing off the coast of the city of Mariupol. Officials did not say who was behind the attack.

Poroshenko has said thousands of Russian troops are in his nation's east, helping the separatists.

Though Russia has denied sending its troops to Ukraine, it defended the rebels' action in the east.

"Washington and Brussels need to ask Kiev authorities to stop shelling the houses, schools, hospitals and so on because you leave militia with no choice but to stand up to protect their people," Russian Foreign Minister Sergei Lavrov said.

Lavrov: 'Let us sit down and talk'

"Let's not ask militia to lay down their weapons and allow themselves to be killed."