BRUSSELS: NATO leaders on Monday agreed to step up their collective defence "against all threats, from all directions," according to their final statement. NATO said it would adapt to climate-reated security challenges, called on Russia to drop its designation of two allies - the United States and the Czech Republic - as "unfriendly countries" and committed funds to the Kabul airport. It said it would respond to Russia"s growing nuclear arsenal and called on Iran to stop all ballistic missile activities. In a first for the Western military alliance, it said China was posing "systemic challenges" for the 30-nation pact.