Asian currencies were confined to narrow ranges and sluggish movements on Wednesday due to ambiguity over the outcome of the approaching Group of Seven meeting in Florida.
Statements before the February 6 and 7 meeting suggest the United States wants the G7 to focus on structural reforms.
Security fears in the United States and speculation that the G7 would not take any strong action to stop the dollar's descent took the yen to new 3-1/2 year highs.
The yen's rise boosted Asian currencies overnight, but trading slackened as Asian markets opened and even the yen was reined in by the fear of Japanese intervention.
Japan was suspected of intervening in the forex market again this week after spending a record amount in January to keep the rising yen from dampening exports.
The Korean won was quoted around 1,168 per dollar for most of the morning, off Tuesday's high of 1,161.
The Taiwan dollar struck a fresh 1-1/2 year high of 33.23, and then settled into dull ranges.
The Singapore dollar was slightly firmer at 1.6930/40 per dollar and the Thai baht crept up to 39.04/08, recovering from the previous day's low of 39.22.
"It is very tough to call what is going to happen to dollar/Asia going into G7. Probably nothing will happen," said Peter Redward, currency strategist with Deutsche Bank.
"Markets are much more cautious going into G7 this time than they were last time and the reaction coming out of G7 could be quite different as well," he said.
But analysts said it was tough to take positions in currencies because the G7 could well call for more flexible currency policies, as they did in September, causing Asian currencies to rise.
Or, if it skirted that topic and focused on growth, the upside in Asian currencies would be limited.
The Philippine peso was the exception as it ignored the G7 speculation and stayed weak, near Tuesday's 56.20 closing low, under pressure from oil imports and offshore interests.
Redward recommended buying a basket of Asian currencies, including the Indian rupee, Sing dollar, baht, won and Taiwan dollar, based on a view that there would be some gradual appreciation during the year.
Rising inflation and any move towards flexibility in China's tightly managed yuan would also give that rally momentum, he said.
Yet, there was no point taking on any long positions on the yuan, he said.
"The problem is the market is already factoring in a huge appreciation in the currency. We think that the other Asian currencies offer a more interesting risk-reward."
Chinese yuan non-deliverable forwards showed a 4,000 points premium on the one-year yuan. That prices in a five percent appreciation in the yuan, which is effectively pegged around 8.28 per US dollar, in a year.