By The South Asia Times

TEHRAN - In a dramatic escalation that has thrown the fragile US-Iran ceasefire into jeopardy, Iran's top negotiator and Parliament Speaker Mohammad Bagher Ghalibaf announced Tuesday that Tehran will not participate in a second round of peace talks with the United States, accusing President Donald Trump of seeking "surrender" rather than a genuine agreement.

"Trump, by imposing a siege and violating the ceasefire, seeks to turn this negotiating table — in his own imagination — into a table of surrender or to justify renewed warmongering," Ghalibaf wrote on X.

"We do not accept negotiations under the shadow of threats, and in the past two weeks, we have prepared to reveal new cards on the battlefield," he added .

The announcement came just hours before the scheduled start of the second round of talks in Islamabad, where Pakistan had completed extensive security preparations.

However, Iranian Foreign Ministry spokesperson Esmail Baqai confirmed that the delegation from Tehran will not travel to Islamabad, stating there is a "profound lack of American sincerity".

The Iranian foreign ministry cited multiple reasons for its withdrawal: Washington's "excessive demands," "constant shifts in stance," and the continued US naval blockade of the Strait of Hormuz, which Tehran considers a direct violation of the ceasefire agreement.

"It seems that America is not serious at all," Baqai said during a press conference, alleging that the US is merely "playing the game of blaming Iran" rather than seeking a genuine resolution.

The timing of Iran's announcement -- hours after Trump confirmed he was sending his "A-Team" to Islamabad -- dealt a significant diplomatic blow to mediation efforts. Pakistani Prime Minister Shehbaz Sharif had spoken with Iranian President Masoud Pezeshkian on Sunday in what he described as a "warm and constructive conversation."

The two-week ceasefire, which began on April 8, is set to expire on Wednesday evening, Washington time. Trump told Bloomberg that he is "highly unlikely" to extend it further without a peace deal.

"If they don't take the deal, the United States is going to knock out every single Power Plant, and every single Bridge, in Iran," Trump warned on Truth Social on Sunday.

In a separate post on X, Iranian President Masoud Pezeshkian reinforced Ghalibaf's stance: "The people of Iran will not bow to coercion. Deep historical mistrust in Iran toward the U.S. government's conduct remains, while unconstructive and contradictory signals from American officials carry a bitter message: they seek Iran's surrender".

Ghalibaf's warning of "new cards on the battlefield" suggests Iran has been preparing military options during the two-week lull in fighting. The Iranian Revolutionary Guard Corps has already warned that it will target any vessel attempting to transit the Strait of Hormuz without authorization.

Iranian state media reported that the decision to reject further talks stems from Washington's "excessive demands, unrealistic expectations, constant shifts in stance, repeated contradictions, and the ongoing naval blockade, which it considers a breach of the ceasefire".

With the ceasefire set to expire in less than 48 hours and both sides hardening their positions, the prospect of a renewed conflict appears increasingly likely. The US has maintained its naval blockade of Iranian ports, and Trump has made clear that he views military action as a viable alternative to diplomacy.

The world now watches as the clock ticks toward what could be the resumption of one of the most volatile conflicts in the Middle East.