In the Greater China region, the Hang Seng index in Hong Kong fell by around 1.32 percent as of 3:31 a.m. HK/SIN.
The Shanghai composite also slipped by 1.49 percent to close at around 2,568.10 — its lowest since November 2014 — while the Shenzhen composite declined by 1.178 percent to end the trading day at about 1,281.08.
The moves in China came as new reserve requirements for lenders went into effect, in a move by the People's Bank of China which is expected to inject 750 billion yuan (around $108.4 billion) into the banking system.
In Japan, the Nikkei 225 fell by 1.87 percent to close at 22,271.30, while the Topix index slipped by 1.59 percent at 1,675.44, with most sectors ending the trading day lower.
Meanwhile, South Korea's Kospi also saw losses of 0.77 percent to close at 2,145.12, with industry heavyweight Samsung Electronics slipping by 0.45 percent and chipmaker SK Hynix falling by 2.9 percent.
In Australia, the benchmark ASX 200 fell around 1 percent to end the trading day Down Under at 5,837.1 with most sectors lower. The heavily weighted financial subindex fell 1.62 percent as major banking shares saw losses — Commonwealth Bank was down 2.09 percent, ANZ fell 1.85 percent, Westpac was lower by 1.59 percent and the National Australia Bank declined by 1.58 percent.
Softbank stock under pressure from Saudi ties
Oil prices increase amid missing Saudi journalist case
"The alleged murder of the Saudi journalist in their embassy in Turkey opens a new source of risk, as President Trump threatens "punishment". Any Saudi retaliation will presumably mainly come through reduced oil supply and higher prices. That won't help market sentiment," Robert Carnell, chief economist and head of research Asia-Pacific at ING, said in a morning note.
|NIKKEI||Nikkei 225 Index||22271.30||-423.36||-1.87%|
|HSI||Hang Seng Index||25445.06||-356.43||-1.38%|
|ASX 200||S&P/ASX 200||5837.10||-58.60||-0.99%|
|CNBC 100||CNBC 100 ASIA IDX||7559.18||-101.04||-1.32%|
US-China trade war in focus
The Japanese yen was at 111.73 against the dollar after strengthening from levels above 113.8 last week, while the Australian dollar traded at $0.7127 after seeing gains from around 0.705 in the previous week.
— CNBC's Fred Imbert, Mike Calia and Evelyn Cheng, along with Reuters, contributed to this report.