South Africa back Nortje for T20 World Cup
The tournament will be played in the United States and West Indies from June 1 to 29.
Nortje, 30, has not played an international match since suffering a back injury during a one-day series against Australia in September 2023 and has struggled for form in the current Indian Premier League.
His seven wickets have cost 42 runs each and he has conceded 13.86 runs an over.
But Walter said he backed the quality of the player who was South Africa's leading bowler at the 2022 T20 World Cup in Australia.
"He has another month before the World Cup and I have no doubt he will hit his straps," said Walter.
"It's good to see that his speed is up. The one thing that Anrich has that separates him from others is raw pace, not many guys can bowl at 150 (kilometres an hour)."
He said he had picked bowlers who he believed would be able to strike in the early stages of matches.
"Taking the top four wickets in the first 10 overs is a large factor in winning games," he said.
Nortje, Gerald Coetzee, Kagiso Rabada and Marco Jansen will spearhead South Africa's fast bowling attack but Walter also named three specialist spin bowlers in Keshav Maharaj, Tabraiz Shamsi and Bjorn Fortuin for what he said are likely to be varied conditions in the USA and the Caribbean.
South Africa have been drawn in Group D of the 20-team tournament.
Their first three matches, against Sri Lanka, Netherlands and Bangladesh, will be at the custom-built Nassau County International Stadium near New York.
Their final group match against Nepal will be in Saint Vincent in the West Indies.
The match between South Africa and Sri Lanka on June 3 will be the first to be played at the new stadium, which will feature a drop-in pitch imported from Adelaide, Australia.
2It is incredibly exciting to be going to a new venue which has literally been created for the World Cup," Walter said of playing in New York.
"It creates a level playing field because no one really knows what we're going to get. The ability to respond quickly to conditions will be imperative."
South Africa have played in all eight previous T20 World Cups but have only advanced from the group stages twice. They reached the semi-finals in 2009 and 2014.
Quinton de Kock and David Miller will be playing in their fifth T20 World Cups, while fast bowler Kagiso Rabada will make his fourth appearance.
South Africa's squad includes two players uncapped at T20 international level, wicketkeeper-batsman Ryan Rickelton and fast bowler Ottniel Baartman.
South Africa provisional squad
Aiden Markram (capt), Ottniel Baartman, Gerald Coetzee, Quinton de Kock (wkt), Bjorn Fortuin, Reeza Hendricks, Marco Jansen, Heinrich Klaasen, Keshav Maharaj, David Miller, Anrich Nortje, Kagiso Rabada, Ryan Rickelton (wkt), Tabraiz Shamsi, Tristan Stubbs
Travelling reserves: Nandre Burger, Lungi Ngidi