Military action could halt the flow of crude oil imports to South Korea, Japan and China, which together account for 34 percent of seaborne oil trade globally, the consultants said in a Wednesday report.
Under a "worst case scenario," China could permit the release of oil from strategic reserves "for the first time since it started building these 3-4 years ago," said Chris Graham, product suite director for gas and LNG at Wood Mackenzie.
South Korea and Japan could take similar action and both countries have emergency reserves to cover 90 days' worth of demand. Japan may accelerate the re-commissioning of nuclear power generators to compensate for any squeeze on imported oil and gas in the event of a conflict.
For China, its domestic oil production would provide a buffer, but the proximity of key producing basins to the North Korean border leaves the country vulnerable to disruption.
"China has domestic oil production options, although up to 58% of this could be at risk of shut-in in the event of escalating tensions," Graham said.
Around 1.5 million of China's 3.95 million barrels per day crude production comes from the North China basin, with the nearest field located 200 kilometers (124 miles) from the North Korean border, according to Wood Mackenzie.
Another 0.8 million barrels per day is produced from the Songliao Basin, which lies approximately 400 kilometers from the border, the consultancy said.
North Korea fired a missile on Tuesday — believed to be the intermediate-range Hwasong-12 — that flew over Japan and broke up into three pieces after flying 2,700 kilometers, far short of its 4,000-kilometer range.
Global oil markets would be "severely affected" in the event of a regional conflict that affects South Korea, Japan and China, where around 65 percent of Asia's refining capacity is located, Wood Mackenzie said. But on the other hand, it added, "regional stockpiling and increased logistics costs could equally lead to a short-term price premium."