Iran and Israel traded attacks on Tuesday as Tehran defiantly refused to reopen the Strait of Hormuz and accept a ceasefire deal on the eve of a deadline set by U.S. President Donald Trump to agree to his demands or get “taken out.”

But in what could be a sign of progress, the Iranian ambassador to Pakistan said “positive and ?productive endeavors” by Islamabad to mediate an end to the war were “approaching a critical, sensitive stage.”

Iran has rejected a U.S. proposal brokered by Pakistan for an immediate ceasefire and the lifting of its effective blockade of the strait, followed by talks ?on a broader peace settlement within 15 to 20 days, according to a source aware of the plan.