"So, if there is a ship beyond that and doing whatever it is doing, then what can anybody do in terms of law. You cannot concoct law," he said.
The vessel, MV Seaman Guard Ohio, whose crew included eight Indians, was intercepted and detained by the Indian Coast Guard east of Tuticorin on Saturday.
An FIR has been registered against 10 crew members and 25 guards of the detained ship by the Tamil Nadu Marine Police for illegally carrying arms and ammunition.
Another case under the Essential Commodities Act has been registered against the crew for buying 1,500 litres of diesel illegally with the help of a local shipping agent.
Sandhu refused to see any "political connotations" in the ship carrying 31 assault rifles and around 5,000 rounds of ammunition, which were seized by the Coast Guard.
"I do not see any element having any political connotations....It is a straight matter of law. Let the investigators do the job," he said.
The Deputy NSA said an FIR has been registered and investigations are being carried out by the Q branch of the CID of Tamil Nadu Police.