Helmut Sonnenfeldt: Protege and rival of Henry Kissinger

If naturalised German Jews seemed to run American foreign policy for much of the 1970s, Henry Kissinger wasn't the only reason. Another was Helmut Sonnenfeldt, friend, protégé, hatchetman and on occasion rival of Kissinger, and also a prime architect of the Nixon era policy of détente with the Soviet Union.

Indeed Sonnenfeldt, though never a president or even Secretary of State, had the rare distinction of a diplomatic philosophy named after him: the so-called "Sonnenfeldt Doctrine" that advocated peaceful co-existence with Moscow and, it was said by critics, accepted that Eastern Europe was legitimately within the Soviet sphere of influence.

Sonnenfeldt always disputed that interpretation, insisting it rested on a wrong understanding of the "organic relationship" between Moscow and its satrapies that he urged at a meeting of US ambassadors to the region in early 1976. But it reflected the intense belief in realpolitik he shared with Kissinger, then Secretary of State, whose counsellor Sonnenfeldt was, and whose background was remarkably similar.

Helmut Sonnenfeldt was a six-year-old boy in Berlin when the Nazis came to power. In 1938 his Jewish parents, both physicians, concluded that the future held nothing but menace, and sent him and his elder brother Richard to boarding school in England as a first step in moving the entire family out of Germany.

The plan succeeded. Walter and Gertrud Sonnenfeldt settled in Baltimore, Maryland, and in 1944 the 18-year-old Helmut joined them – along with Richard, who after the war would become interpreter and subsequently chief interrogator for American prosecutors at Nuremberg – and took American citizenship. By mid-1945 Helmut was serving with the US occupation forces in Germany, where he met and became friends with Kissinger, then deployed with American military intelligence.

After returning to the US, Sonnenfeldt studied international relations at Johns Hopkins University and took a masters degree in 1951. The following year he joined the State Department as a specialist in Soviet and Eastern European affairs. All the while, however, he remained in touch with Kissinger and moved with him to the White House in 1969 as an assistant when Kissinger was picked as national security adviser by the newly elected Richard Nixon.

The intrigues and backstabbings at the Nixon White House, and not least at the National Security Council, were legendary: at least once Kissinger had Sonnenfeldt wiretapped after the alleged leaking of documents. But a tough school produced a talented crop: not only Sonnenfeldt, but also the likes of Lawrence Eagleburger, Winston Lord, John Negroponte and Anthony Lake, diplomatic stalwarts of future administrations, both Republican and Democratic.

The similarities between Sonnenfeldt and Kissinger, three years his elder, extended well beyond their common origins. They shared an intellectual arrogance. But both were pragmatists open to reasoned argument, and, when needed, tireless negotiators. Both believed that world stability depended on a modus vivendi with the rival superpower. And, having personally experienced what can happen when German regimes run amok, both were suspicious (and perhaps jealous) of Willy Brandt, who became West German chancellor in 1969 and beat Washington to the détente punch with his Ostpolitik, calling for closer ties between the Germanys and reconciliation with the wartime foes of Poland and the Soviet Union.

The next seven years, under presidents Nixon and Ford, produced a string of US-Soviet agreements, from arms control to the 1975 Helsinki Accords ratifying Europe's postwar borders in the best realpolitik tradition but opening a crack in the door of human rights – never a Kissinger priority – that would contribute to the unravelling of the Communist bloc a decade and a half later.

When Kissinger became Secretary of State in 1973 Sonnenfeldt followed him to Foggy Bottom as special counsellor. "He was with me in practically every negotiation I conducted with the Soviets," Kissinger said, "an indispensable collaborator." Not least during a mid-1970s trip to the Soviet Union when Leonid Brezhnev asked Kissinger what he thought his luxurious hunting lodge might be worth in the US property market. Perhaps $400,000, ventured Kissinger, to the chagrin of the Soviet leader, who was clearly expecting a much higher figure. "More like $2m," Sonnenfeldt quickly interceded, averting diplomatic disaster.

Rupert Cornwell

Helmut Sonnenfeldt, diplomat: born Berlin 13 September 1926; US State Department 1952-69; National Security Council 1969-73; Counsellor, State Department 1973-1977; married 1953 Marjorie Hecht (one daughter, two sons); died Chevy Chase, Maryland 18 November 2012.