Yaounde - President Paul Biya on Thursday called for international help to stop Boko Haram, a day after the Islamist terrorist group threatened to escalate attacks in Cameroon."From Mali to Somalia to the Central African Republic, these terrorists have the same agenda," said Biya. "A global threat requires a global response."Biya responded to a video message posted on YouTube on Wednesday, in which Boko Haram leader Abubakar Shekau said the insurgents will target Cameroon more forcefully if its army continued operations against them."Oh Paul Biya, if you don't stop this, your evil plot, you will taste what has befallen Nigeria ... Your troops cannot do anything to us," Shekau said in Arabic.Biya declared war on Boko Haram at a security summit in May, after the group started to frequently infiltrate into Cameroon from neighbouring Nigeria.The president deployed more than a thousand troops and special units to the Far North Region. The soldiers have killed dozens of insurgents over the past months.Biya said he was disappointed, however, that a multi-national security force planned during a summit in Paris had not yet been set up.