A recent spate of positive developments have pointed towards a de-escalation of a trade conflict between the world's two-largest economies.
The benchmark Singapore index, which will trade for a shorter session ahead of the Christmas holiday, was buoyed by telecom and industrials.
Jardine Strategic Holdings was up as much as 0.8%, while Singapore Telecommunications rose 0.9%.
However, investors in most other markets are choosing to wait until next year to see how long the current thaw in Sino-U.S. relations lasts.
"Granted, there were bright spots with the White House suggesting that the "Phase-1" deal is within grasp... but the tough "Phase-1" negotiations reveal that further progress would require significant concessions on both sides, which lifts the bar for further trade gains," Vishnu Varathan, a senior economist at Mizuho Bank, said in a note.
Losing the most in the region, Malaysian equities saw their worst session in five days, with utilities and healthcare weighing down on the index in thin trading.
Index heavyweights Petronas Gas and Top Glove Corporation Bhd fell about 3% and 1% respectively.
Thailand stocks shed as much as 0.3%, a day after central bank governor raised concerns about the economy, signalling room for further rate cuts.
"The outlook moving forward remain gloomy as the country's effort to control currency appreciation by cutting key interest rates, among others has no significant impact," an MIDF Research note said.
Industrials and telecom were the biggest drag on the index, with G J Steel PCL being the top percentage loser on it.
The Vietnam index was set to snap three straight sessions of gains, dragged down by industrials and financials.
Meanwhile, Philippine and Indonesian markets were closed until Wednesday.
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SOUTHEAST ASIAN STOCK MARKETS AS AT 0339 GMT
Market Current Previous close Pct Move
Singapore 3223.28 3214 0.29
Bangkok 1571.04 1573.57 -0.16
Kuala Lumpur 1607.93 1614.18 -0.39
Ho Chi Minh 955.87 959.43 -0.37
Change so far in 2019
Market Current End 2018 Pct Move
Singapore 3223.28 3068.76 5.04
Bangkok 1571.04 1563.88 0.46
Manila 7872.6 7,466.02 5.45
Jakarta 6305.91 6,194.50 1.80
Kuala Lumpur 1607.93 1690.58 -4.89
Ho Chi Minh 955.87 892.54 7.10
By Shruti Sonal