Most emerging Asian currencies weakened on Tuesday as the prospects for progress at high-level US-China trade talks this week were hurt by Washington's placement of criminal charges against China's Huawei Technologies Co.
Further undermining the outlook for the talks, set for Wednesday and Thursday in Washington, was China triggering the legal process on Monday for the World Trade Organization to hear Beijing's challenge to US tariffs.
The combination of the US Justice Department's charges against Huawei, which Beijing expressed serious concern over, and China's WTO move may complicate recent hopes of a trade deal between the world's top two economies.
Indonesia's rupiah weakened the most in the region, down 0.2 percent to 14,090 a dollar, but it remained among the top gainers this year.
Malaysia's ringgit and the Thai baht both fell 0.1 percent, while the Philippine peso was flat.
While most Asian currencies were weaker in early trade, losses were capped by the US dollar holding flat and some optimism that there still could be positive developments from discussions between China's Vice Premier Liu He and US Trade Representative Robert Lighthizer and others.
The safe-haven yen gained against the greenback, while the dollar index was roughly flat, but hovered around its lowest level in two weeks.
"Having relented on the US government shutdown, President Donald Trump needs to show a win on trade at his State of the Union address on 5 February," DBS said in a note.
The actions by the US Justice Dept. "show that it would not be enough for China to buy more US goods. America wants China to make structural reforms especially on its intellectual property practices", the bank said.
The Indian rupee and China's yuan were largely unchanged.
Tuesday brings the start of a two-day US Federal Reserve policy meeting, where Chairman Jerome Powell is widely expected to acknowledge growing risks to the US economy as global momentum weakens.
Investors will be keenly looking for further confirmation that the US monetary authority will pause its rate-hike cycle.
The interest rate futures market is pricing in no Fed hikes this year. Last year, the dollar enjoyed a solid rally as the Fed raised rates four times because of a robust economy, to the dismay of regional emerging market currencies.
In a note, Maybank analysts said "a case of extended pause in Fed's tightening cycle would further reinforce our bias to lean against USD strength."