"The unfolding developments after the signing of the joint statement, the statement of Pak NSA contradicting what was claimed by India on the understanding reached and now unprovoked firing across LoC confirms that what was claimed by the government and the BJP as a historic breakthrough was a historic blunder," senior party spokesman Anand Sharma said.
Sharply reacting to the developments, he said that besides giving a befitting response to Pakistan, the Modi must apologise for "compromising and diluting" India's case for bringing perpetrators of Mumbai terror attacks to justice.
Insisting that the policy of engagement with Pakistan has been "non-serious, casual and inconsistent", the Congress leader said that there has never been a roadmap for a sincere engagement which addresses India's principal concerns.
The Congress reaction came as amid heightened tension India warned Pakistan of "effective and forceful" response to unprovoked firing and cross-border terrorism.
India's blunt message followed a series of ceasefire violations along the LoC in Jammu and Kashmir by Pakistan which resorted to mortar shelling of Indian areas over the past two days. India responded in kind and both sides said they had suffered casualties.