W A S H I N G T O N / TEHRAN: As President Donald Trump kept the world guessing whether his country would join Israel`s bombardment of Iranian nuclear and missile sites, Iran`s Supreme Leader Ayatollah Ali Khamenei vowed never to back down, warning the US of `irreparable damage` if it gets entangled in its conflict with Israel.

The Wall Street Journal reported that Trump had told senior aides a day earlier that he had approved attack plans for Iran, but had withheld a final order to see if Tehran would abandon its nuclear programme.

`I may do it, I may not do it. I mean, nobody knows what I`m going to do, Trump told reporters on Wednesday when asked if he had decided whether to launch strikes, also claiming that Tehran had reached out to him to negotiate.

After Trump`s audacious demand for Tehran`s `unconditional surrender` a day earlier, Khamenei said in a speech on Wednesday that `this nation will never surrender`, and called the ultimatum `unacceptable`.

His statement came a day after Trump boasted that the US could assassinate Khamenei.

The supreme leader rebuked the president in a recorded speech played on television, his first appearance since the Israeli onslaught began.

The Americans `shouldknow that any US military intervention will undoubtedly be accompanied by irreparable damage,` he said.

`Intelligent people who know Iran, the Iranian nation and its history will never speak to this nation in threatening language because the Iranian nation will not surrender.

US plans A source familiar with internal discussions said Trump and his team were in the White House Situation Room considering options that included joining Israel in strikes against Iranian nuclear installations.Trump claimed Iran had evensuggested sendingofficials to the White House to negotiate on Tehran`s nuclear programme to end Israel`s air assault, but added that it was `very late.

He claimed that Iran was `a few weeks away` from having a nuclear weapon and told reporters that `a deal could still happen`.

As of Wednesday afternoon, Trump said he has not yet arrived at a final decision on potential US involvement in the conflictbetween Israel and Iran.

`I have ideas as to what to do, but I haven`t made a final I like to make the final decision one second before it`s due, you know, because things change. I mean, especially with war, things change with war. It can go from one extreme to the other,` he told the media in the Oval Office.

Asked about what would happen if the Iranian regime falls, Trump said, `I have a plan for everything, but we`ll see what happens.

Got a ways to go,` reiterating that Iran `should have` made a nuclear deal.

Meanwhile, the New York Times reported that Iran would accept US President Donald Trump`s offer to meet soon, citing a senior Iranian official.

The newspaper, citing the official, added that Iranian Foreign Minister Abbas Araghchi would accept such a meeting to discuss a cease-fire with Israel.

Sixth day of aerial war Israel and Iran exchanged fire again on Wednesday, the sixth day of strikes in their most intense confrontation in history.

The Israeli military said on Wednesday it had launched a new wave of attacks targeting missile systems and storage sites in western Iran, as it kept up its barrage of strikes across the country.

Israeli Defence Minister Israel Katz said air force jets had destroyed Iran`s `internal security headquarters`, while AFP journalists reported hearing blasts in Tehran.

`Air Force jets have just destroyed the internal security headquarters of the Iranian regime,` Katz said in a statement.

Meanwhile, Iran launched hypersonic missiles in a new wave of attacks against Israel, state TV reported.

The Fattah hypersonic missiles `have successfully penetrated the Israeli regime`s defenses,` state TV reported.

World worried The possibility of the US militarily entering the Middle Eastern theatre had alarm bells ringing around the world.

UN Secretary-General Antonio Guterres on Wednesday warned against any `additional military interventions` in the Middle East.

`Any additional military interventions could have enormous consequences, not only for those involved, but for the whole region and for international peace and security at large,` he said in a statement.

Chinese Foreign Minister Wang Yi said Wednesday his country was concerned that the conflict between Israel and Iran `may get out of control`, warning that the region could slide into an `abyss`.

`Israel`s acts of disregarding international law and international rules have caused the situation in the Middle East to suddenly become tense, and China is also deeply concerned that the situation may get out of control,` Wang told his Egyptian counterpart in a phone call Wednesday, China`s foreign ministry said.

The same day, in a separate call with Oman`s foreign minister, Wang said the two countries `cannot sit idly by and let the region slide into an unknown abyss`. He said reaching a ceasefire agreement was a `top priority`.

Amnesty International urged Israel and Iran to spare civilians as their conflict escalates and alarm grows over the death toll.

`Further escalation of these hostilities risks unleashing devastating and far-reaching consequences for civilians across the region and beyond,` Amnesty Secretary General Agnes Callamard said.-Agencies