WASHINGTON (Reuters) - NATO must boost security cooperation with Russia and streamline operations to face new challenges -- both military and civilian -- in coming years, U.S. Secretary of State Hillary Clinton said on Monday.

Clinton said new partnerships, including with Cold War foe Russia, will help NATO to take on growing transnational threats including nuclear proliferation, terrorism, piracy and cyber security.

“While Russia faces challenges to its security, NATO is not among them,” Clinton told a Washington think tank, stressing that a new U.S. plan for European missile defense was no threat to Moscow.

“Just as Russia is an important partner in efforts to prevent nuclear proliferation, so should it be in missile defense,” she said. “And we invite Russia to join NATO in developing a missile defense system that can protect all citizens of Europe and Russia.”

Clinton’s speech to the Atlantic Council was the latest effort by the Obama administration to reassure European allies that Washington will hold tight to transatlantic ties despite growing preoccupation with China, Iran and other hotspots.

It was also a fresh gesture to Moscow, which has grown increasingly nervous over new U.S. plans for European missile defense as well as plans to continue expanding NATO membership.

NATO is now undertaking a major review to assess its structure and goals for coming decades, and Clinton said it was crucial that member states take the opportunity to re-imagine the alliance as a broader, more flexible organization.

“You don’t win by fighting the last war,” she said.

RUSSIA AS PARTNER

She said that NATO must guard against both terrorism and outright military threats, including nuclear proliferation and missile development in countries such as North Korea and Iran.

And she said Russia -- for so long the focus of NATO’s fears -- could emerge as a partner, including on missile defense.

President Barack Obama announced last year he was shelving Bush-era plans to install a land-based missile shield to guard against long-range missile threats from Iran -- a move which pleased Moscow, which had opposed the shield idea.

But Moscow has expressed doubts about the new U.S. strategy, which centers on sea-based interceptors and a second-phase of land-based systems that U.S. officials say will be better able to counter short- and medium-range missiles, which they now deem the chief threat from Iran and elsewhere.

Clinton said that while the United States had “real differences” with Russia in several areas, it was also committed to working with Moscow to advance common interests.

“We want a cooperative NATO-Russia relationship that produces concrete results,” she said.

She said the idea of partnership should be central to a new streamlined NATO, which needs a more powerful secretary general to achieve its goals.

The United States, which in the past has been ambivalent about suggestions that NATO work more closely with the European Union, was also now fully behind deeper cooperation between the two organizations.

“We do not see the EU as a competitor of NATO -- we see a strong Europe as an essential partner,” she said.

And she said NATO’s new challenges would increasingly include civilian aid and construction -- as seen in Afghanistan, where civilian assistance efforts are being implemented in parallel with the growing U.S.-led war against the Taliban.

“For too long, our Alliance has been hamstrung by those who argue that NATO is an exclusively military organization and oppose attempts to develop -- or even discuss -- the Alliance’s capacity to take on civilian tasks,” she said.

“Our common experience in Afghanistan has shown that the Alliance cannot accomplish its missions using purely military tools. “