Crude kept rising following its biggest weekly gain since late 2016 after President Donald Trump said he would impose “major additional sanctions” on Iran, exacerbating tensions in the oil-rich Middle East.

Futures in New York rose as much as 0.9% after surging 9.4% last week. Trump tweeted about the sanctions, days after he abruptly called off a plan for air strikes against the Islamic Republic in retaliation for the downing of a U.S. Navy drone. He also said he’s willing to hold talks with Iranian leaders with “no preconditions” to ensure the nation never acquires a nuclear weapon.

After falling to the lowest level in almost five months in mid-June, oil has rallied as escalating tensions between Washington and Tehran threaten to disrupt crude flows. Hopes that China and the U.S. will restart trade negotiations have also aided prices, with Trump set to meet with Chinese President Xi Jinping at the G-20 summit in Japan this week. There are as yet no details on the new sanctions on Iran, although the nation has managed to keep exporting some energy despite a U.S.-imposed ban from early May.

“The arrow is pointing upwards at the moment,” said Michael McCarthy, chief market strategist at CMC Markets Asia Pacific Pty in Sydney. “Neither side wants a war here but there is national pride at stake on both sides,” he said, adding that technical indicators were also pointing to further gains.

West Texas Intermediate for August delivery rose 32 cents, or 0.6%, to $57.75 a barrel on the New York Mercantile Exchange at 10:21 a.m. in Singapore after climbing as much as 52 cents earlier. It settled 1.4% higher on Friday, capping a weekly rally that was the biggest since Dec. 2, 2016.

Brent for August settlement advanced 17 cents, or 0.3%, to $65.37 a barrel on London’s ICE Futures Europe Exchange, after closing up 1.2% on Friday. The benchmark crude contract traded at a premium of $7.61 to WTI.