The Wall Street Journal reported, citing White House officials, that U.S. President Donald Trump has become increasingly frustrated as the Iran war enters its fifth month, having initially believed the conflict would end within a few weeks, while diplomatic options begin to shrink.

Some of Trump's advisers worry that the war, which has led to rising energy prices, declining approval ratings for the U.S. president, and the deaths of more than a dozen soldiers, is weakening Republican chances in the upcoming midterm elections.

During a recent White House meeting, Trump launched a scathing attack on Iranian leaders, using harsh language, according to a source who heard the remarks, as reported by the newspaper.

Trump has sought for months to gradually end the war. He announced a ceasefire in April after threatening to end 'the entire Iranian civilization.' In June, he declared that the U.S. and Iran had signed a memorandum of understanding to reopen the Strait of Hormuz. But brief periods of calm quickly dissipated, and the two sides returned to fighting.

According to sources, the U.S. president has grown more skeptical in recent days about the possibility of achieving lasting peace through negotiations with Iran.

A senior U.S. administration official told the newspaper, 'Trump believes that Iran only understands military force,' and that 'he sees no good options other than continuing strikes.'

The U.S. is reinforcing its troops and weapons in the Middle East to give Trump stronger military options if he decides to escalate, while he threatened, in remarks to Axios, a major escalation of the war.

White House spokesperson Karoline Leavitt said: 'The United States signed a memorandum of understanding with Iran, but Tehran violated it, fired on commercial ships, and killed American soldiers. President Trump will not stand idly by and allow this terrorist behavior to continue.'

She added that Iran 'is paying the price for its behavior, and will continue to pay it, until it sits at the negotiating table in a way that President Trump deems productive.'

Declining Confidence in Diplomacy

As the war continues, Trump's confidence in the ability of the U.S. and Iran to find a diplomatic solution to the conflict has waned.

Sources told the newspaper that Trump has told his advisers it is difficult to know who represents the top leadership, and that every time the U.S. believes it has made progress at the negotiating table, Iran continues its attacks.

Last month, Trump was so enthusiastic about the possibility of signing a memorandum of understanding with Tehran to reopen the Strait of Hormuz that he ignored his Republican allies who said the Iranians would not abide by the agreement, according to a senior U.S. official. Trump said at the time he wanted to get it done.

Sources said Trump's envoys, Jared Kushner and Steve Witkoff, still believe a deal with the Iranians is possible. But other advisers have expressed skepticism about reaching a peace agreement.

The war has created divisions in the conservative coalition that Trump once fully controlled, worrying some Republicans close to the White House.

Trump's longtime allies have used their platforms to express concerns about the war's impact on Republicans in the November midterm elections.

Steve Bannon, Trump's former adviser, said: 'Netanyahu dragged us into a horrific conflict full of lies. People see with their own eyes what is happening.'

A senior U.S. administration official told the newspaper that Trump has expressed displeasure with Israeli Prime Minister Benjamin Netanyahu, and has even told his aides at times that he does not want to speak with or meet him. The official added that the Israelis sought to arrange a meeting between Netanyahu and Trump.

Netanyahu was expected to visit the United States next week for the funeral of Senator Lindsey Graham, but the plans have not been finalized.

Trump still says, privately and publicly, that Iran should not possess a nuclear weapon. He has told some close associates that he believes he can break the Iranians' will through an intense bombing campaign, according to the newspaper.