Andrew Tabler: The hand extended to Syria is also intended as a blow to Iran

The appointment of Robert Ford as US Ambassador to Syria is part of the Obama administration's general policy of engagement with America's foes. Its timing to coincide with Under Secretary of State William Burns' visit to Damascus, however, has a wider purpose. The move is part of a massive diplomatic push in the Middle East to isolate and roll back Syria's ally, Iran.

Change in Syria will be slow and incremental. During the cold war between Damascus and Washington in the aftermath of Rafic Hariri's February 2005 assassination in Beirut, the Assad regime pursued policies the US intelligence establishment never thought they would, including facilitating foreign jihadists' entry to Iraq, and pursuing a nuclear programme with North Korea's help. While Damascus survived the Bush administration's pressures – including tough sanctions and diplomatic isolation – the very things Damascus did to survive have made reconciliation with the US now much harder than most expected.

It remains to be seen whether Washington extending its hand will lead to changes in Syria's attitude to America. The US is planning to test Syria on key issues. In the short term, these include seeing if Damascus is willing to cut off the path into Iraq for jihadists, and return to negotiations (be they direct or indirect) with Israel. Policymakers agree that only a peace treaty with Israel will lead Damascus to sever ties with Hizbollah, Hamas and back away from if not break its alliance with the Islamic Republic of Iran. Burns' visit is that effort's first step.

A year of US engagement with Syria has shown that sanctions have had a much greater effect than expected. Damascus has asked Washington to drop or ease these measures. This gives Washington unexpected leverage at a key time in attempts to change Syria's behaviour and promote talks with Israel. Sanctions have been regarded as punitive measures, but they could, ironically, be a path to peace.

Improving US-Syrian relations will have a lot to do with Syria's foe, Israel. Syria is adamant it will not sever its relationship with either Hizbollah or Hamas, short of a peace treaty with Israel. This means the degree to which relations can improve is limited unless real peace is achieved.

The writer is author of the forthcoming book In the Lion's Den: Inside America's War with Assad's Syria (IB Tauris)