Military spokesperson Brig-Gen. Moti Almoz wrote online on Sunday that the group used their military service "to express political opinions" in the letter sent last week, saying "disciplinary treatment would be sharp and clear", Xinhua reported.
"There is no place for refusal of service in the Israel Defense Forces. There are disagreements and there are political views," Almoz wrote, adding that the military takes a "severe" view over what he said was "exploitation of military service to express a political stance".
Last week, the group of 43 veterans of the elite intelligence unit 8200 launched a letter to Prime Minister Benjamin Netanyahu, Israel Defence Forces Chief of Staff Benny Gantz and intelligence chief Aviv Kochavi, while also forwarded it to Israeli media outlets Thursday.
In the letter they said that the information gathered by the unit "harms innocent Palestinians and is used for political prosecution by creating divisions without the Palestinian society by recruiting collaborators," whereas the purpose, they said, is to "deepen Israel's control of the occupied territories."
"This does not allow for people to lead normal lives, and fuels more violence, further distancing us from the end of the conflict, " the letter read.
While Israeli citizens are being protected from extensive surveillance, that is not the case with the Palestinians and that the intelligence gathered, in many cases, "prevents defendants from receiving a fair trial in military courts," as the evidence against them is not revealed, the letter added.
In interviews with media outlets following the letter's publication, those veterans expressed grievances about what they termed "abusive collection" of Palestinians' private information, such as sexual orientation, health and financial issues, which they said is ultimately used to extort individuals into becoming informants for Israel's intelligence agencies.
"We are conscientiously incapable of continuing to serve this system," they asserted in their letter.
They added that millions of Palestinians have been living under Israeli military rule for more than 47 years. "This is not an inevitable result of the state's efforts to protect itself but rather the result of choice."
The letter has drawn controversy, as two hundred members of the unit wrote a response letter on Sunday denouncing the 43 veterans.
Netanyahu and his defence minister both slammed the letter, saying there's no place for refusal and politics in the army.
Unit 8200, one of the most prestigious units in the Israeli army, monitors electronic communication and conducts surveillance, as is performed by the US National Security Agency.