Xi Jinping has returned to the White House for the first time in 11 years, but his diplomatic pledges on this visit are being met with widespread scepticism — an unsettling signal for security in the Indo-Pacific.

• Xi visited the White House again on the 24th; the previous occasion was a joint press conference with Obama in the Rose Garden in 2015.

• At the time, he publicly stated that China "had no intention to militarise" its construction work in the Spratly Islands, a remark seen as a conciliatory signal.

• The reality proved otherwise: Mischief Reef, Subi Reef and Fiery Cross Reef were successively built up into military strongholds, equipped with military runways, hangars, deep-water berths and radar stations, with air-defence and anti-ship missiles routinely deployed.

• China's coast guard has used water cannon against Philippine resupply vessels, its military aircraft have had close encounters with US and Australian aircraft, and Chinese naval and air activity around Taiwan has grown steadily more frequent.

• That 2015 pledge has since reset the benchmark by which Washington assesses Beijing's diplomatic credibility.

Outlook: Whatever new posture or new commitments this visit brings, Washington and countries in the region are unlikely to take them at face value, and tensions in the South China Sea and the Taiwan Strait are unlikely to ease in the near term.