Britain is bringing out the big gunships in case of a no-deal Brexit.

Four of the Royal Navy’s vessels are being deployed to protect UK waters from European Union fishing boats if the two sides can’t reach a nearly $1 trillion trade agreement by the Dec. 31 deadline, the Sun reported.

Two will be at sea by Jan. 1; the other two are on standby, ready to head out with only a few hours’ notice.

Fishing — especially France’s right to fish in British waters — has been a key sticking point during months of on-and-off negotiations. On Friday, British Prime Minister Boris Johnson and the EU’s top official, Ursula von der Leyen, acknowledged the chances of striking an agreement are slim to none.

The gunships will patrol the English Channel and Irish Sea, and — if no pact is inked — will intercept any EU boats. The navy’s vessels, in the most serious cases, would seize and then escort an EU boat to the nearest British port.

“Nobody is going to be firing warning shots against French fishermen,” a navy insider told the Guardian. “Firearms are only used when there is danger to life.”