Security has been beefed up at all vital installations in India and abroad - especially the Indian high commission in Islamabad - following the execution of the lone surviving 26/11 attacker, Mohammad Ajmal Amir Kasab on Wednesday. In Islamabad, the Pakistani authorities tightened security at the Indian high commission following a note verbale - a semi-formal diplomatic communication - from New Delhi, Hindustantimes reported Friday. A government source said the Pakistani Taliban had openly announced it would strike Indian interests everywhere. Whats more, the operational capabilities of the Lashkar-e-Taiba (LeT), which trained and sent out Kasab and nine others to Mumbai, are intact. While the home ministry alerted all states and the BSF in border areas, the Intelligence Bureau quietly directed all its regional offices to remain on high alert even before Kasabs execution. In the national capital region, Delhi Police authorities have stepped up vigil at vulnerable spots. \"We are focusing on hotels and embassies and the areas VIPs frequent,\" a senior officer said. Police teams are also making announcements at marketplaces, asking citizens to inform police about any suspicious object. Meanwhile, Tehrik-e-Taliban Pakistan spokesman Ihsanullah Ihsan said if India did not hand over Kasab\'s body to his family or to the Taliban, Indians would be captured and killed and their bodies would not be returned. Earlier, Jabiuddin Ansari alias Abu Jundal, one of the handlers of Kasab, told Indian investigators that the detention of Zaki-ur-Rehman Lakhvi, the alleged mastermind of the 26/11 attack, in Adiala jail of Pakistan is nothing but a sham. Zaki\'s own men from LeT guard him in jail. He has access to all communication tools -- including a satellite phone - for planning and directing more strikes. The rest of the perpetrators of the 26/11 attacks, such as Sajid Mir, have never been put on trial even for the sake of pretense. Intelligence inputs suggest Sajid Mir is still trying to recruit new cadre for another terror strike in India. Almost nine months after the Mumbai attacks, Sajid Mir reportedly wrote an email to David Colan Headley, another 26/11 accused being tried in the US, in July, 2009 saying he had some investment (attack) plans with him.