Gavin Williamson said those who are intent on bringing “destruction, death and bloodshed” onto the streets of Britain are being “hunted down” and that threat “eliminated”.
In an interview with The Daily Mail, Mr Williamson, who filled the vacancy left last month after Michael Fallon was pressured to quit the British Cabinet, said: “A dead terrorist can’t cause any harm to Britain.”
In October, the terror laws watchdog said authorities should look to “reintegrate” the “young” and “naive” jihadis who travel to warzones, rather than prosecute them, on their return to the country.
Max Hill QC, the Independent Reviewer of Terrorism Legislation, spoke of “losing a generation” of men and women by automatically using the courts to punish them.
But Mr Williamson said the armed forces were working “right across the globe” to ensure jihadis are never able to come back to the country in the first place.
He said: “I do not believe that any terrorist, whether they come from this country or any other, should ever be allowed back into this country.”
Mr Williamson told the paper the role of jihadis in foreign fields should not be underestimated, with “much of what is done to activate” threats to Britain done in places such as Libya, Iraq and Syria.
He added: “Our job in terms of eliminating will not stop this year, will not stop next year, it is something we have got to continue to pursue.”
Hundreds of British citizens are known to have travelled to Syria to fight with Islamist groups during the course of the six-year conflict.
Meanwhile, foreign secretary Boris Johnson is due to deliver a speech on Thursday in which he will praise British efforts around the world to tackle terrorism.
He will say: “Every day around the world I can tell you that British serving men and women are putting their lives at risk to roll up terrorist networks, to expose what they are doing, to thwart them and bring them to justice.
“They are making good on what the Prime Minister has rightly called the unconditional commitment of the British people to the security of our European friends, not just in this continent but beyond.”
On Tuesday, the director general of MI5 told the Cabinet that a total of nine Islamist terrorist plots have been thwarted in the UK over the past year. - PA