TEHRAN, April 19 (Xinhua) -- With a fragile U.S.-Iran ceasefire nearing its expiry, uncertainty once again clouds the outlook for the Middle East. The stop-and-go situation in the Strait of Hormuz -- briefly reopened and then shut again by Iran -- has added to the volatility.

The episode highlights deep-rooted disagreements over maritime access and nuclear issues, suggesting tensions may remain elevated in the near term.

BACK-AND-FORTH IN HORMUZ

Following the ceasefire in Lebanon -- once a major flashpoint in the early days of the U.S.-Iran truce -- Iranian Foreign Minister Seyed Abbas Araghchi said on Friday that the Strait of Hormuz was completely open to all commercial vessels.

U.S. President Donald Trump welcomed the move, but stressed that the U.S. naval blockade on Iran would remain in full force until Washington's transaction with Tehran is "100 percent complete."

Just a day later, Iran's Khatam al-Anbiya Central Headquarters announced the resumption of strict control over the Strait of Hormuz, accusing Washington of violating the ceasefire and "continuing its banditry and piracy under the so-called title of blockade."

The Navy of Iran's Islamic Revolution Guards Corps later confirmed that the Strait of Hormuz would remain closed until the United States lifts its naval blockade on the waterway, warning that no vessel should move from its anchorage in the Persian Gulf or the Gulf of Oman, and any approach to the strait would be deemed "cooperation with the enemy" and targeted accordingly.

Following Tehran's reversal, Trump convened a White House Situation Room meeting on Saturday morning to discuss developments in the strait and negotiations with Iran. The meeting reportedly included Vice President JD Vance, Secretary of State Marco Rubio, Defense Secretary Pete Hegseth and other senior officials.

"They (Iran) can't blackmail us," Trump said at a White House event.

MAJOR DIFFERENCES

On April 11, Iran and the United States, under Pakistan's mediation, held a round of intense negotiations in Islamabad, but no major breakthrough was achieved. Iranian Parliament Speaker Mohammad Baqer Qalibaf, who led Tehran's delegation, said that progress had been made, but the two sides remain far apart on key issues.

According to statements from both sides and media reports, the United States and Iran have recently exchanged views on three key issues, with significant gaps remaining.

First, the fate of Iran's highly enriched uranium remains unresolved. Trump said on Friday that the United States would work with Iran to remove its enriched uranium. CNN, citing informed sources, reported that Washington is prepared to unfreeze 20 billion U.S. dollars in Iranian assets in exchange for Tehran's handing over its stockpile, a proposal rejected by Iranian Deputy Foreign Minister Saeed Khatibzadeh as "impossible."

Second, disagreement persists over Iran's right to enrich uranium. Trump on Friday claimed that Iran had agreed to suspend its nuclear program indefinitely, a claim denied by an anonymous senior Iranian official in an interview with CNN the following day. Meanwhile, U.S. sources familiar with previous talks said Washington had proposed a 20-year suspension of Iran's enrichment activities, while Tehran countered with a five-year pause -- a proposal the United States did not accept.

Third, tensions remain high over freedom of navigation in the Strait of Hormuz. A U.S. official told The Wall Street Journal on Saturday that the U.S. military is preparing to board and potentially seize Iran-linked oil tankers and commercial ships in international waters in the coming days. On the same day, a senior U.S. official told Axios that without a diplomatic breakthrough, fighting between the two sides could resume within days.

Despite ongoing contacts and mediation efforts, key differences between the United States and Iran remain unresolved, making a swift agreement unlikely, analysts say. ■