He said he expects he will not get an answer, and perhaps the committee should discuss the matter in a future closed meeting.
"We know about the ISIS threat," Marais said.
He was referring to a threat that ISIS will start fighting within South Africa's borders, if South Africa were to get involved in the conflict in Mozambique's Cabo Delgado province.
This is according to reports on ISIS's latest newsletter, Al-Naba, News24 reported on Tuesday.
An organisation linked to ISIS, Ahlu Sunnah Wal Jamaah, has been waging a violent insurgency in Mozambique's northernmost province, Cabo Delgado, which has taken more than 1 000 lives.
It started in 2017, but the violence has escalated in recent months. They want to establish an extremist form of Islamic law in the province, even though their motives have been questioned by some as more compelled by greed.
The question by Marais was the last time a word was spoken on the topic in Wednesday's meeting.
Several high-ranking officers were in attendance, but none offered an answer or comment on the matter.
Neither Minister of Defence and Military Veterans Nosiviwe Mapisa-Nqakula, nor her deputy Thabang Makwetla, nor Secretary of Defence Sam Gulube, was present at Wednesday's meeting.
At a previous meeting of the committee, on 3 June, Gulube said special forces' operations are "classified" and perhaps the committee could arrange that it is "discussed under closed doors".
Later in June, Mapisa-Nqakula in a written parliamentary reply gave the first public expression of concern from the government that the violence in Mozambique could spread.
"Defence Intelligence can confirm that there is an increase of Islamic insurgency activities currently in the province of Cabo Delgado, Mozambique, and these have the potential to spread to other provinces and neighbouring Southern African Development Community states," read Mapisa-Nqakula's answer.
Marais told News24 that there is clearly more to the matter than has thus far been made public.
He said Parliament's relevant oversight committees must be informed, without jeopardising South Africa's military integrity.