North Atlantic Treaty Organization Secretary General Jens Stoltenberg cautioned that any deliberate damage to the alliance’s critical infrastructure would warrant a response after an undersea gas pipeline was ruptured in a suspected act of sabotage in Finland. “If it is proven to be a deliberate attack on NATO critical infrastructure, then this will be serious but will also be met by a united and determined response from NATO,” Stoltenberg said ahead of a meeting of NATO defense ministers in Brussels.