EU leaders on Thursday adopted a declaration urging Russia to de-escalate tensions caused by its military build-up along the border with Ukraine. They warned that an invasion would bring a severe cost in response, including restrictive measures coordinated with partners. The EU leaders also called on Moscow to engage in diplomatic talks through an existing forum with Paris, Berlin and Kiev. Moscow has already dismissed western claims that Russia may be preparing to invade Ukraine. It says the military buildup is in response to growing NATO activities on its borders.