BEIJING (Reuters) - Oil markets on Monday shrugged off U.S. President Donald Trump's threat to hit buyers of Russian oil with tariffs as the shock value of the barrage of threats from the White House begins to wear thin with jaded traders.

Trump's off-the-cuff proposal to hit any country buying Russian oil with a 25% to 50% tariff would be significant for oil markets if it turned into an order, but analysts and traders questioned whether the president's latest threat was serious.

"There's an element of fatigue with the announcements from the U.S. administration on tariffs and sanctions," said ING's head of commodities strategy Warren Patterson.

"So I suspect until we get something more concrete, the market is not going to overreact to this," he said.

Oil prices dipped on Monday with the more active June Brent crude futures down 0.2%, to $72.59 a barrel by 0028 GMT, and the U.S. West Texas Intermediate crude lower by 0.3%, to $69.18 a barrel.

China and India are major buyers of Russian crude and their acquiescence would be crucial to making any secondary sanctions package seriously hurt exports from the world's second largest oil exporter.

Recent U.S. sanctions on Moscow have led Chinese state oil companies to shy away from Russian oil, with Sinopec and Zhenhua Oil halting purchases, while two others scaled back volumes as they assessed compliance.

However, on Monday morning several Chinese traders were unfazed by the latest threat. Three who spoke with Reuters all said Trump's constant brinksmanship meant they discounted what he said.

"We're all numb now, oil prices are not responding," said one trader who spoke on condition of anonymity. "It's no use listening to Trump anymore."

"It's hard to tell what the impact would be as Trump is always bluffing, his words have lost credibility," said a second.

If the tariffs became a serious threat, markets would look to how strictly the policy would be enforced and whether the Organization of the Petroleum Exporting Countries would ramp up production to make up for any drop in Russian exports, analysts said.

The secondary sanctions imposed on Venezuelan oil last week could serve as a model for markets to assess the impact of a similar set of policies against Russia, said Patterson.

Chinese buyers have already paused purchases ahead of those sanctions taking effect on Wednesday. Traders and analysts expect some sales to resume as buyers find workarounds unless Beijing issues a blanket ban.