Brussels, Jumada I 1, 1437, Feb 10, 2016, SPA -- NATO took the first step Wednesday to boost its deterrence against Russian aggression in the east of the alliance, as it seeks to juggle what Secretary General Jens Stoltenberg called the "most challenging" security threats in a generation, dpa reported. Relations between NATO and Russia in the last two years have reached their worst level since the Cold War, following Moscow's actions in Ukraine, where it is accused of supporting pro-Russian separatists and has annexed the Crimean peninsula. But the alliance must also stay "agile" and be prepared for other threats, Stoltenberg warned. NATO is confronted with challenges including the conflict in Syria, the migration crisis this has triggered and the spread of terrorism. NATO has previously taken steps to reassure its eastern members, who have felt particularly threatened by Russia. The new plan aims to go further, with a combination of flexible ground forces and rapidly deployable reinforcements to deter any potential aggressor. "NATO defence ministers agreed on an enhanced forward presence in the eastern part of our alliance," Stoltenberg said following talks in Brussels. "This will be multinational to make clear that an attack against one ally is an attack against all," he added. The new defence framework will include rotational troop deployments, exercises and infrastructure to pre-position equipment and rapidly deploy reinforcements, Stoltenberg said. The details - including troop numbers and national contributions - are to be hashed out by military planners over the coming months, ahead of NATO's Warsaw summit in July. -- SPA 21:59 LOCAL TIME 18:59 GMT www.spa.gov.sa/w