Asian shares mostly declined Tuesday, despite a rally on Wall Street boosted by easing oil prices, as regional investors still weighed the impact from the recent joint U.S.-Japan currency intervention. This was reported by Qazaqyia.kz citing Associated Press.

Japan's benchmark Nikkei 225 slipped 0.6% to 63,369.85, as the U.S. dollar inched up to 157.63 Japanese yen from 157.18 yen. The euro cost $1.1511, little changed from $1.1514. The dollar was trading at 160-yen levels before the intervention.

Some analysts said the effectiveness of such an intervention remains uncertain as it doesn't address the fundamental economic reasons behind the currency fluctuations, including inflation, interest rates and the relative strengths of the economies.

"A U.S.-backed operation carries far more signaling weight than Tokyo acting alone, and the pledge of further action will give speculators pause. But any U.S. contribution will probably be constrained by size," a report by BMI, a unit of Fitch Solutions, said.

Matthew Ryan, head of market strategy at global financial services firm Ebury, noted the latest effort could have some impact because it appears to signal a real change in monetary policy rather than just a one-time defensive move.

"This is an historic and meaningful development for the yen, which materially improves confidence in our mildly bullish call for the currency," he said.

South Korea's Kospi also declined. Specific figures were not provided, but a general downturn was observed in the region.

In the U.S., falling oil prices helped boost major indices on Wall Street, but Asian markets focused on the aftermath of the currency intervention. Analysts say the long-term effect of the intervention is doubtful because it does not change economic fundamentals.

Japan's intervention in the currency market was backed by the U.S., which drew mixed reactions from investors. Some experts believe this step could temporarily halt the yen's depreciation, but long-term solutions require economic reforms.

Currently, market participants are closely watching the next steps of the U.S. and Japan, as well as inflationary pressures in the global economy. The movement of major indices in Asia reflects instability in global markets.