"I want to know from Congress and its allies why they are demoralizing security forces by asking for proof of the air strikes against terror camps. Why are they issuing such statements that benefit our enemies?" Modi asked addressing NDA's Sankalp rally in Patna where he formally launched NDA's campaign for the upcoming Lok Sabha polls in Bihar.

"Congress and its allies are doing things which are enough for making the enemies smile. At a time when there was a need to speak as one against terror factories, 21 parties in Delhi came together to speak against the NDA. People won't forgive them," Modi said.

Modi reminded thousands of people gathered to hear him at Gandhi Maidan here that when the entire country is rejoicing over the IAF's successful airstrikes on terror camps in Pakistan's Balakot, "a few of our own people have raised suspicion on such a strikes".

Modi cautioned people against opposition's 'Mahagathbandhan' agenda, which was "personal and for their own family." "Had the Mahamilavat government been there, there wouldn't have been any decision or development because they have a habit of developing themselves," Modi said.

The Opposition, he said, has a one-point agenda -- eliminate or remove Modi, who is a 'chowkidar' and 'pradhan sewak' of the country and its people.

"Instead of considering the good work done by the Modi government, the Opposition nowadays is in a competition to abuse the 'chowkidaar', but rest assured, this 'chowkidaar' of yours is as alert as ever," he added.

Since early Sunday thousands of NDA leaders, workers and supporters gathered in the Bihar capital -- with hundreds thronging the venue since Saturday night -- to hear the Prime Minister at the Sankalp rally.

Modi and Bihar Chief Minister Nitish Kumar shared dais at the political rally after a decade. Both had come together last time at a rally in 2009 in Ludhiana in Punjab.

Security was tight at the Sankalp rally in Gandhi Maidan. It was on October 27, 2013 when Gandhi Maidan was rocked by serial bomb blasts. Modi was then the BJP's prime ministerial candidate. At least six people had been killed and around 100 injured in the blasts.

On Sunday, all roads virtually led to the Gandhi Maidan as participants marched to the venue waving saffron and green flags of BJP, JD-U and LJP of Union Minister Ram Vilas Paswan.

Hundreds of vehicles carrying thousands of people were stuck in the outskirts of Patna and Gandhi Setu that connects north Bihar to Patna.

The NDA had hired 18 trains and nearly 5,000 buses to ferry supporters to the Sankalp rally.

Senior Superintendent of Police Garima Malik said nearly 4,000 police personnel had been deployed in and around the sprawling ground.

Police also set up dozens of watch towers and 60 door-frame metal detectors. Bomb disposal and anti-terrorist squads too have been deployed, he said.