ISLAMABAD, April 22 -- Last-minute ceasefire talks between the United States and Iran looked uncertain Tuesday as a two-week truce was set to expire and both countries warned that, without a deal, they were prepared to resume fighting. US Vice President JD Vance, expected to lead US negotiators if talks continue, called off a trip to Pakistan, a US official said. And Iran said it hadn't decided whether to participate. Pakistani leaders, including Prime Minister Shehbaz Sharif, worked intensively late Tuesday to get both sides to agree to a second round of ceasefire talks, according to two officials who spoke on condition of anonymity because they were not authorized to speak to the media. The ceasefire was set to expire Wednesday. Iranian Foreign Ministry spokesman Esmail Baghaei told Iran's state TV there has been "no final decision" on whether to attend because of "unacceptable actions" by the US, apparently referencing its recent blockade in the Strait of Hormuz. As Vance put on hold traveling for more ceasefire talks, Trump's special envoy Steve Witkoff and son-in-law Jared Kushner were expected in Washington on Tuesday afternoon for consultations about how to proceed, said an official, who spoke on condition of anonymity to discuss internal administration deliberations. The official cautioned that Trump could change his mind on negotiating with Iran at any minute, and declined to predict what would happen if the current ceasefire expires without another meeting in Islamabad but noted that Trump retains options short of restarting airstrikes. Both sides remain dug in rhetorically. U.S. President Donald Trump has warned that "lots of bombs" will "start going off" if there's no agreement before the ceasefire deadline, and Iran's chief negotiator said that Tehran has "new cards on the battlefield" that haven't yet been revealed. The ceasefire, which began April 8, could be extended if talks resume, though Trump said in an interview Tuesday with CNBC: "Well, I don't want to do that." "We don't have that much time," Trump said, adding that Iran "had a choice" and "they have to negotiate." White House officials have said that Vance would lead the American delegation, but Iran hasn't said who it might send. Iranian state television on Tuesday broadcast a message saying that "no delegation from Iran has visited Islamabad . so far." On Tuesday, the U.S. said its forces boarded an oil tanker previously sanctioned for smuggling Iranian crude oil in Asia. The Pentagon said in a social media post that U.S. forces boarded the M/T Tifani "without incident."...