[9] During this time Kasrils worked with Yusuf Dadoo, Joe Slovo and Jack Hodgson and they formed a special committee (1966–76) to develop underground activities in South Africa from the United Kingdom.

He trained various people including Raymond Suttner, Jeremy Cronin, Ahmed Timol, Alex Moumbaris, Tim Jenkin, and Dave and Sue Rabkin, with the aim of establishing underground propaganda units in South Africa.

The protest was led by senior ANC leaders including South African Communist Party Secretary General Chris Hani, Cyril Ramaphosa, Steve Tshwete and Ronnie Kasrils.

Kasrils led an unarmed group in an attempt to break through the Ciskei Defence Force lines to enter Bisho.

[12] After the first fully democratic elections in South Africa in 1994, Kasrils became a member of the Transitional Executive Council's (TEC) Sub-Council on Defence.

[14] He gained international attention after penning a "Declaration of Conscience by South Africans of Jewish Descent" in 2001 against Israeli policies in the occupied territories.

[16] In a two-part essay "David and Goliath: Who is Who in the Middle East"[17][18] published in the ANC's theoretical journal Umrabulo in late 2006 and early 2007, Kasrils outlined a history of Israel-Palestine since 1948 very critical of Israeli governments and military actions.

Parts of the essay were published in the Mail&Guardian in a summarised form under the title "Rage of the Elephant: Israel in Lebanon.

"[19] The article caused considerable controversy,[20] when Kasrils, commenting on the results of civilian deaths following the Israeli invasion of Lebanon in July 2006, and referring to the Israeli leadership, noted: "... we must call baby killers 'baby killers' and declare that those using methods reminiscent of the Nazis be told that they are behaving like Nazis.

[28] In April 2014, he launched the "Vote No" campaign alongside fellow ANC member and former government minister Nozizwe Madlala-Routledge.

[29] In December 2014, Kasrils was elected to the national working committee of the newly created United Front, a workers' party led by the National Union of Metalworkers of South Africa (NUMSA), and also spoke favourably of the Economic Freedom Fighters, a newly formed leftist opposition party.

[31] Kasrils has written books on Bertrand Russell and poetry and articles on politics, defence and water & forestry issues.

Kasrils published a book in 2017 on his experience of working with then-South African President Jacob Zuma called A Simple Man.