Defence Secretary Penny Mordaunt has said it is her “personal priority” that servicemen and women will not be “pursued unfairly” over claims of wrongdoing decades ago.
Ms Mordaunt, who took on her role last week, said personnel should not be “victims of unfounded allegations”.
It comes after Tory MP Johnny Mercer withdrew his support for the government over historical prosecutions.
He urged the PM to end the “abhorrent process” affecting some veterans.
Mr Mercer has previously called for legislation to prevent anyone accused of crimes linked to the Troubles in Northern Ireland from being prosecuted.
But Sinn Féin’s Linda Dillon said there could be “no immunity or impunity for British forces guilty of crime, collusion and murder in Ireland”.
“No one is above the law, all victims and survivors should have the same access to processes of truth and justice,” she said.
Six former soldiers are now facing prosecution over Troubles-era killings.
The cases relate to Daniel Hegarty; Bloody Sunday; John Pat Cunningham; Joe McCann (involving two ex-soldiers); and Aidan McAnespie.
Not all the charges are murder.
The Public Prosecution Service in Northern Ireland said that of 26 so-called legacy cases it has taken decisions on since 2011, 13 related to republicans, eight to loyalists, and five are connected to the Army.
Ms Mordaunt, a naval reservist, said the situation had “dragged on for far too long” and it was “time for action”.
“We owe it to those who take the greatest risk in the service of their nation,” she said.
“We will always hold our armed forces and the chain of command to account but I want to ensure our service personnel are not going to be victims of unfounded allegations, as we saw in the case of IHAT (Iraq Historic Allegations Team), or pursued unfairly for events that took place decades ago.”
On Wednesday, Mr Mercer sent a letter to Theresa May saying she should end “elderly veterans being dragged back to Northern Ireland” to face possible prosecution.
He said he would only vote with the Conservatives on Brexit legislation.
Mr Mercer, a member of the Commons Defence Committee, said: “As you know, the historical prosecution of our servicemen and women is a matter that is personally offensive to me. Many are my friends; and I am from their tribe.”
In response, the prime minister’s official spokesman said the issue of the prosecutions of veterans was taken “extremely seriously”.
“In relation to Northern Ireland prosecutions, we have been clear the system to investigate the past needs to change to provide better outcomes for victims and survivors of the Troubles and to ensure members of our armed forces are not disproportionately affected,” he said.