From Revolutionary Democracy:
The participation of Bukharin and his group in terrorist activity directed against Stalin has been asserted persistently in the Soviet literature. Aside from the official party and state documentation it has been mentioned by L.M. Kaganovich in his conversations with Feliks Chuyev.  What is remarkable about Jules Humbert-Droz’s last conversation with Bukharin held in early 1929, in which Bukharin indicates that his opposition group had taken the decision to utilize individual terror against Stalin, is that it emanates from a source which is sympathetic to Bukharin. We are informed by Stephen Cohen in his favourable biography of Bukharin that Jules Humbert-Droz was one of the few Comintern leaders who remained loyal to Bukharin after the Sixth Congress of Comintern in 1928.  Another striking feature about the conversation given below is that despite the widespread availability of Humbert-Droz’s memoirs it finds no mention in the voluminous literature on Bukharin which has burgeoned in the west in recent decades. It is a glaring omission in Stephen F. Cohen’s highly acclaimed biography of Bukharin which on other points does refer to the writings of Jules Humbert-Droz.
The significance of the conversation with Bukharin was not lost on the reviewer of the memoirs of Humbert-Droz in the pages of the ‘Times Literary Supplement’ more than thirty years ago:
‘But the report of the conversation in the memoirs contains one passage which… brings up the reader with a start:
Bukharin also told me that they had decided to use individual terror to get rid of Stalin.
Humbert-Droz replied that he was opposed to individual terror (i.e. assassination), of which the Bolsheviks had never approved. He makes no further comment on the point. It has been generally supposed that, when the authorities hurled changes of conspiracy and terror at the opposition, they were victims of an overheated imagination or were inventing excuses to justify their own reprisals. Perhaps the assumption has been unduly naive. Perhaps, if Bukharin did say this, words had not yet been translated into plans. Do serious conspirators talk like this to outsiders? For the present a disconcerting question-mark must be appended to this strange, almost casual revelation.’ 
The anonymous reviewer of the ‘Times Literary Supplement’ deserves kudos for alerting observers of Soviet history to Bukharin’s conversation on the question of assassinating Stalin. But it is not necessary to put a ‘disconcerting question-mark’ on this revelation. Jules Humbert-Droz was not an ‘outsider’ but a Bukharin loyalist at the time of this conversation (he later joined the ranks of Swiss Social-Democracy). Moreover, Bukharin’s words do appear to have been ‘translated into plans’. We may refer to one of the conversations of L.M. Kaganovich with the Soviet poet and chronicler Feliks Chuyev which recalls the cross-examination of Bukharin in a Politbureau meeting:
‘Yes, there was his confrontation with Kulikov. He was a Muscovite. At the meeting of the Politbureau members, Kulikov addressed Bukharin: ‘You remember Nikolai Ivanovich, how you took me by the arm and we walked along the Vozdvizhenka, and I said to you: ‘Why are you wasting your time there, when it is time to act…’ Bukharin inquires ‘but where are your people?’ ‘Who would act?’ ‘Well people could be found’. ‘And why don’t you act yourself? Participate in terrorist acts?’
“I never said that’ shouted Bukharin. How do you deny this when you wanted the surnames [familia – ed.] of the persons I had listed – said Kulikov who was a member of the Moscow Committee, Secretary of the Regional Committee, a tanner by trade and very politically aware.
‘Sergo [Ordzhonikidze ed.] asks Bukharin whether he had said this or not.
‘Yes’, answered Bukharin.
‘How could you?!
‘I thought that Sergo was about to hit him.’
Augmenting the statement of Kulikov was that of Slepkov, another Bukharin loyalist who was also cross-examined in the confrontation at the Politbureau meeting :
“Did Bukharin send you to the Northern Caucasus?’ – ‘Yes’. ‘What tasks did he give you?’ – ‘The task was to find out the mood of the Kazakhs, and the residents of the Kuban and the Don whether they were prepared for something or not?’ Once again they asked Bukharin: ‘Did you say this to him?’ He hesitated and said ‘Yes’.
‘Once again Sergo sprang up. ‘Is it really possible that you might have said this?’ – ‘Then I was opposed to all the politicians of the CC, but today – no.’ 
It is evident that both those near to Bukharin and those inimical to him – Jules Humbert-Droz and Lazar Kaganovich respectively – concur that he raised the question of the use of individual terror against Stalin.
1. Feliks Chuyev, ‘Thus Spake Kaganovich’, ‘Revolutionary Democracy’ Vol. 1, No. 2, September 1995, pp. 32-33.
2. Stephen F. Cohen, ‘Bukharin and the Bolshevik Revolution’, Oxford University Press, New York, 1980, p. 394.
3. ‘Times Literary Supplement’, 23.6.1971, p. 733.
4. Feliks Chuyev, loc. cit.
Before leaving I went to see Bukharin for one last time not knowing whether I would see him again upon my return. We had a long and frank conversation. He brought me up to date with the contacts made by his group with the Zinoviev-Kamenev fraction in order to coordinate the struggle against the power of Stalin. I did not hide from him that I did not approve of this liaison of the oppositions. ‘The struggle against Stalin is not a political programme. We had combatted with reason the programme of the trotskyites on the essential questions, the danger of the kulaks in Russia, the struggle against the united front with the social-democrats, the Chinese problems, the very short-sighted revolutionary perspective, etc. On the morrow of a common victory against Stalin, the political problems will divide us. This bloc is a bloc without principles which will crumble away before achieving any results.’
Bukharin also told me that they had decided to utilise individual terror in order to rid themselves of Stalin. On this point as well I expressed my reservation: the introduction of individual terror into the political struggles born from the Russian Revolution would strongly risk turning against those who employed it. It had never been a revolutionary weapon. ‘My opinion is that we ought to continue the ideological and political struggle against Stalin. His line will lead in the near future to a catastrophe which will open the eyes of the communists and result in a changing of orientation. Fascism menaces Germany and our party of phrasemongers will be incapable of resisting it. Before the debacle of the Communist Party of Germany and the extension of fascism to Poland and to France, the International must change politics. That moment will then be our hour. It is necessary then to remain disciplined, to apply the sectarian decisions after having fought and opposed the leftist errors and measures, but to continue to struggle on the strictly political terrain’.
Bukharin doubtlessly had understood that I would not liase blindly with his fraction whose sole programme was to make Stalin disappear. This was our last meeting. Manifestly he did not have confidence in the tactic that I proposed.
Courtesy: Jules Humbert-Droz, ‘De Lénin à Staline, Dix Ans Au Service de L’ Internationale Communiste 1921-31’, A la Baconniére, Neuchâtel, 1971, pp. 379-80. Translated from the French by Vijay Singh.