Union Home Minister Amit Shah on Tuesday launched a sharp political and administrative attack on West Bengal Chief Minister Mamata Banerjee, alleging that her government has failed to stop illegal infiltration through the state’s borders, turning it into a matter of national security. Addressing a press conference in Kolkata during his three-day visit to the state, Shah asserted that unchecked infiltration under the Trinamool Congress (TMC) rule posed a threat not only to Bengal but to the entire country.