NATO leaders agreed a 41-page communique at their summit Monday outlining the alliance's approach to old threats -- and new.

From Russia and China, to Afghanistan and attacks in space, here are five key conclusions from the gathering of the 30 allies in Brussels.

Russia troubles 

An aggressive Russia clearly remains top worry for the 72-year-old alliance set up to help contain the Soviet threat in the wake of World War II. 

"Russia's growing multi-domain military build-up, more assertive posture, novel military capabilities, and provocative activities... increasingly threaten the security of the Euro-Atlantic area and contribute to instability along NATO borders and beyond," the communique said. 

"Russia's nuclear strategy and comprehensive nuclear weapon systems modernisation, diversification, and expansion, including the qualitative and quantitative increase of Russian non-strategic nuclear weapons, increasingly support a more aggressive posture of strategic intimidation."

The allies denounced Moscow's "hybrid actions", "widespread disinformation campaigns", "malicious cyber activities", and election interference directed against NATO members. 

"Until Russia demonstrates compliance with international law and its international obligations and responsibilities, there can be no return to 'business as usual'," the statement said.  

"We will continue to respond to the deteriorating security environment by enhancing our deterrence and defence posture."

China 

The language on China was the most hotly watched topic ahead of the summit -- as NATO under pressure from Washington increasingly directs more attention to Beijing. 

"China's stated ambitions and assertive behaviour present systemic challenges to the rules-based international order and to areas relevant to Alliance security," the communique said. 

The leaders said they were "concerned" by  China's coercive policies -- and highlighted its "rapid development" of nuclear arsenal, greater military cooperation with Russia, and "lack of transparency and disinformation".

But NATO also held out the prospect for "a constructive dialogue with China where possible".

"Based on our interests, we welcome opportunities to engage with China on areas of relevance to the Alliance and on common challenges such as climate change," the leaders said. 

"Reciprocal transparency and understanding would benefit both NATO and China."

Afghanistan 

The leaders insisted they were opening a "new chapter" in relations with Afghanistan as they rush to withdraw their forces by a US deadline of September 11. 

"We affirm our commitment to continue to stand with Afghanistan, its people, and its institutions in promoting security and upholding the hard-won gains of the last 20 years," they said. 

It said that the alliance would continue to provide funding and training for Afghanistan's security forces and would keep paying to maintain the civilian functioning of Kabul airport. 

Cyber, space 

Cyber threats featured prominently in the conclusions as the leaders endorsed a new "Comprehensive Cyber Defence Policy".

The allies repeated their decision that a cyber attack could trigger NATO's mutual defence clause -- broadening that to include a series of attacks. 

"Allies recognise that the impact of significant malicious cumulative cyber activities might, in certain circumstances, be considered as amounting to an armed attack," the statement said.

For the first time as well leaders also said that an attack on infrastructure in space -- such as satellites -- could trigger Article 5. 

"We consider that attacks to, from, or within space present a clear challenge to the security of the Alliance, the impact of which could threaten national and Euro-Atlantic prosperity, security, and stability, and could be as harmful to modern societies as a conventional attack. Such attacks could lead to the invocation of Article 5," it said.  

"A decision as to when such attacks would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis."