The security situation in India's neighbourhood is a matter of concern as the country is surrounded by many "failed states", Defence Minister A K Antony said on Saturday."The security situation around is a matter of concern. We are surrounded by many failed states. The security scenario in those states is a matter of concern for us also," he said, addressing an Armed Forces Veterans Rally organised as part of Army Mela-2008 in Thiruvananthapuram.Though the country's unity and integrity faced threat from different sources, the armed services were capable of meeting any challenge through their dedication, vigil and competence, he said."Right from August 15, 1947, when the country attained freedom, we have been facing lot of threats to our unity and integrity from external sources. As years pass by, the threats are increasing, not only from one source but many sources," Antony said.He said a grateful nation could never forget the sacrifices made by soldiers and their families, he added.THEIR SHOULD BE ZERO TOLERANCE: PRANABIn the wake of blast in Mehrauli, the government today said there has to be "zero tolerance" for terrorism and asserted that it is taking "stern" measures to bring the culprits behind the explosion to book.Soon after the blast, External Affairs Minister Pranab Mukherjee, who chairs Cabinet meetings in absence of Prime Minister Manmohan Singh, held deliberations with Home Minister Shivraj Patil on the situation."I condemn in strongest terms this barbaric act of violence leading to the loss of an innocent life," Mukherjee said after the meeting. "There has to be zero tolerance for such acts of terror," he said.Noting that he had reviewed the situation with the Home Minister, Mukherjee said "the government is committed to bring the culprits to book and stern measures are being taken towards this end."