ROME - NATO Secretary-General Anders Fogh Rasmussen highlighted on Friday the importance of "smart defense" as the answer to pressure on defense budgets.

European allies need to continue investing in security, otherwise it "will risk losing its relevance and we cannot afford them," Rasmussen told a press conference in Rome after meeting Italian Prime Minister Mario Monti ahead of a NATO summit in May in Chicago.

"Smart defense," emphasizing multinational cooperation in the acquisition of new capabilities, will be a central issue at the Chicago summit.

"In Chicago I want Europe to adopt a new mindset for how re-approach security, making cooperation on defense programs a priority rather than a last resort, and that is what we call smart defense," the NATO chief said.

Rasmussen said he discussed with Monti the difficult economic situation in Italy and in Europe, as "economy and security are interlinked, and a weak economy means that we have less resources for security."

"How to provide security in a time of economic austerity, and how to deal with great uncertainty in the world with fewer economy resources at home" will be a challenge NATO has to face in order to balance economy and security, which is necessary for stability, he said.

"We have to keep our defenses up ... and this is also about the role we want Europe to play in the world," Rasmussen stressed.

He called for more cooperation and commitment as "in these tough times it is difficult for some countries alone to acquire or maintain all the capabilities they need, but if they were together they can."

"I am confident that Europe will emerge stronger from the Chicago summit," he added.

On the issue of the missile shield in Europe, Monti said it should not have negative consequences for the dialogue between NATO and Russia, but must be "a prerequisite for a strategic breakthrough in relations between Moscow and the alliance."

The Italian prime minister also called for the strengthening of NATO partnerships with southern Mediterranean countries and the Gulf, which can play an essential role in protecting security and regional stability.