As a statesman, Raja had to work with the imperfect foreign regimes he faced, not with counterparts he might have ideally wished for. This could sometimes make for unpalatable diplomacy with dubious and even repugnant characters. This was the part of his job that he confessed he disliked most and found most trying. “As a foreign minister, I meet people. I form my own impressions. Some of them I find completely distasteful,” he said. “But I cannot afford to let them know about this.” In politics as in diplomacy, at times one had to engage in some dissimulation, he said, “which I find distasteful but which is necessary”.

Few encounters tested his ability to deal with the darker side of diplomacy than negotiating with the notorious henchmen of the Pol Pot regime: Khieu Samphan, Ieng Sary, and the latter's wife, Ieng Thirith, who was also Pol Pot's sister-in-law and the highest-ranking female in the regime. It was an unavoidable part of the tortuous business of forging a new coalition out of three incompatible Kampuchean resistance factions.

Besides the communist Khmer Rouge leaders, there were the two non-communist nationalist leaders: former head of state Prince Norodom Sihanouk, who was based in Pyongyang and Beijing, and former prime minister Son Sann, who was based in Paris. Compared with the Khmer Rouge, these two men were paragons of virtue. But they shared one major weakness as resistance fighters: they lacked the brute military strength of the Khmer Rouge, which was putting up the only credible resistance with its 35,000 troops well armed with Chinese weapons. On the other hand, the non-communist nationalists had a valuable asset that eluded the repulsive and reviled Khmer Rouge: respectability.

If the non-communist groups could join forces with the Khmer Rouge in a united front, they would recast the image of Democratic Kampuchea and sustain international support for the struggle. Together, they could exert greater pressure on Vietnam to accept a political solution and withdraw its forces from Kampuchea. And as part of a coalition representing Democratic Kampuchea at the UN, the two noncommunist nationalist factions could legitimately receive aid, including weapons, from governments sympathetic to their cause – just the way the Vietnamese were being armed by the Soviets, and the Khmer Rouge by the Chinese. That was the strategic logic that underpinned the coalition scheme conceived by Raja, its principal architect.