WASHINGTON — The Republican National Convention this week has portrayed President Trump as a strong commander in chief facing down enemies and demanding more of allies, but the boastful language has glossed over the grand ambitions of his foreign policy that he has been unable to fulfill.

       The president’s audacious nuclear diplomacy with North Korea has fallen apart. Iran defies his “maximum pressure” campaign and refuses to bargain. A White House Israeli-Palestinian peace plan was effectively dead on arrival. And a trade deal with China looks more distant than ever.

       American troops still fight in Afghanistan, where a comprehensive peace agreement remains elusive. In Syria, U.S. forces that the president pledged to remove skirmished this week with troops from Russia, a nation that remains provocative, despite Mr. Trump’s incongruous overtures to President Vladimir V. Putin. In Venezuela, the socialist president, Nicolás Maduro, thumbs his nose at the Trump administration’s explicit efforts to depose him.

       “There’s a lot of unfinished business. At best you can say it’s an ‘incomplete,’” as measured by Mr. Trump’s own standards, said Eric S. Edelman, a former under secretary of defense in the George W. Bush administration.

       Mr. Edelman, an outspoken critic of Mr. Trump who recently signed an open letter with more than 70 other Republican national security professionals condemning the president, said the reality was far worse. Even in cases where Mr. Edelman approved of Trump administration strategy — such as its emphasis on competition with China and Russia — he said Mr. Trump did not seem fully in sync with official policy. “He has no case, really,” Mr. Edelman said.

       Democrats are noting the many unchecked items on Mr. Trump’s to-do list. National Security Action, a group of former Obama administration foreign policy officials, issued a memo this week titled “Four Years of Failed Deals” that criticized Mr. Trump’s actions on China, North Korea, Iran and Afghanistan, among others.

       “Far from brandishing his ‘dealmaker’ credentials, Trump has shown himself to be little more than a snake oil salesman,” the memo said. “His vaunted deals haven’t materialized, and what he has brought forward has tended to be hollow and worth little more than the paper it’s written on.”

       The president and his allies say they are not given enough credit for a series of successes, including several that deliver on promises he made in 2016.

       Mr. Trump withdrew — or “ripped up,” as he put it — from President Barack Obama’s 2015 Iran nuclear deal. And after promising to “bomb the hell out of” the Islamic State, he oversaw a military campaign that led to the terrorist group’s near-total battlefield defeat — even if that campaign was planned and initiated under the Obama administration. In his convention speech on Tuesday night, Secretary of State Mike Pompeo cited those actions, along with the targeted killing in 2019 of the group’s “evil leader,” Abu Bakr al-Baghdadi.

       Speaking from Jerusalem to spotlight Mr. Trump’s relocation of the American embassy there from Tel Aviv in 2018, Mr. Pompeo also praised the president’s pressure campaign against Iran and the missile strike that killed Maj. Gen. Qassim Suleimani, the notorious Iranian military commander, on Jan. 3.

       Other convention speakers emphasized the way Mr. Trump, who has repeatedly vowed to end “endless wars,” has avoided entangling the country in new military conflicts, making him the first American president since Jimmy Carter to not send combat troops into a new theater. “In four years, Donald Trump didn’t start any new wars,” Richard Grenell, his former ambassador to Germany and the acting director of national intelligence, said on Wednesday night.

       But the president has also recently begun to argue that he needs another term to make good on his grandest ambitions. Many American adversaries, he says, are simply waiting him out in hopes of his defeat in November. A Democratic loss, Mr. Trump argues, would force them to capitulate.

       “If and when we win, we will make deals with Iran very quickly, we will make deals with North Korea very quickly,” Mr. Trump said at a news conference this month from his resort in Bedminster, N.J.

       The president has also argued that China hopes he will lose, preferring to start over with former Vice President Joseph R. Biden Jr., the Democratic nominee. Mr. Trump says he can also secure a “better” trade deal with Beijing after November, if he wins, than before.

       Richard Goldberg, a former National Security Council aide in the Trump White House who worked on Iran, said the president had conducted foreign policy well, adding that it was natural for a first-term foreign policy to be inconclusive.

       “There’s only so much that you can accomplish in four years,” he said. “Typically, you set policies and strategies in motion that produce results over two terms.”

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       But Mr. Trump, the master of the media event, would surely prefer tangible done deals to assurances of results just around the corner. In his recent account of working in the White House, John R. Bolton, Mr. Trump’s former national security adviser, wrote that the president in mid-2019 was determined to announce that all American troops would be withdrawn from Afghanistan before the election. “How does it look politically?” Mr. Bolton said the president asked a group that included senior national security officials.

       Mr. Trump did strike a deal last fall with the Taliban that coupled the ending of hostilities between the insurgent group and U.S. forces with a drawdown of American troops, who may soon number about 4,000, from a peak of about 14,000 during his tenure. But that was an interim step toward a larger peace agreement between the Taliban and the Afghan government — one that has made shaky progress amid increased violence and doubts about the Taliban’s good faith. Those talks are finally set to begin this week, but for now, voters will have to settle for the assurance on Tuesday night by Senator Rand Paul, Republican of Kentucky, that Mr. Trump “intends to end the war in Afghanistan” at some future date.

       The president has similarly been thwarted in his efforts to withdraw U.S. troops from Syria, where he has repeatedly pledged a total withdrawal only to see his military commanders insist on a few hundred troops to hunt Islamic State remnants and counter Iranian influence. And there has been no mention this week of the thousands of American soldiers deployed to Saudi Arabia over the past year in response to heightened tensions with Iran.

       In other cases, Mr. Trump has not come within swinging distance of his goals. Growing hostilities with China over the coronavirus pandemic and Beijing’s security crackdown on Hong Kong have severely dimmed prospects of what Mr. Trump has said will be a “tremendously big deal” redefining trade relations. One of his first presidential actions, walking away from Mr. Obama’s Trans-Pacific Partnership, ended international efforts to create a vast trade agreement among North America, South America, Australia, Japan and other Asian allies that was devised to isolate China and counter its growing economic muscle.

       Three surreal meetings with Kim Jong-un, the North Korean leader, have yielded no tangible progress toward that country’s denuclearization. On Tuesday night, Mr. Pompeo was left to say that Mr. Trump had “lowered the temperature” with Pyongyang. Mr. Pompeo mentioned the good news that North Korea had stopped its nuclear and long-range missile tests for now, but he omitted the fact that it continued to produce nuclear material, which is now likely to be enough to produce 20 atomic weapons.

       Mr. Trump’s punishing sanctions on Iran have been a “huge success,” Mr. Goldberg said, choking off money that Tehran uses to meddle in neighboring countries. And the president’s boasts of terminating the 2015 nuclear deal were surefire applause lines at his campaign rallies before they were halted because of the coronavirus.

       Yet Mr. Trump’s ultimate strategic goal of forcing Tehran to negotiate a new nuclear deal remains nowhere in sight. Iran scoffs at the idea of talking to Mr. Trump and has instead resumed aspects of its nuclear program. U.S. allies have also ignored the president’s calls for international sanctions.

       Mr. Goldberg shares Mr. Trump’s confidence that a cash-starved leadership would quickly strike a deal with him if he is re-elected. But it is also possible that Iran will accelerate its nuclear program, leading to a crisis.

       When it comes to the wider Middle East, Mr. Pompeo boasted on Tuesday about the normalization of relations between Israel and the United Arab Emirates that was brokered by the Trump White House, a breakthrough that even his critics say deserves credit. But that achievement is a modest substitute for Mr. Trump’s larger goal of a peace agreement between Israel and the Palestinians, one that if anything appears less likely to be reached after a detailed 181-page plan and three years of efforts by his son-in-law, Jared Kushner.

       Kori Schake, the director of foreign and defense policy studies at the American Enterprise Institute, said the president’s policies “alienate allies but don’t produce outcomes.”

       Some of those allies are annoyed at Mr. Trump’s pressure on them to spend more on collective NATO defense, as convention speakers have boasted this week. But many say the alliance as a whole has been further weakened by the president’s open doubts about its relevance and his continued overtures Mr. Putin. (Restoring friendly relations with Moscow is another of Mr. Trump’s unfulfilled goals, one with little support elsewhere in Washington.)

       Mr. Trump’s withholding of military aid to Ukraine, intended to defend against Russia, as way to pressure Kyiv to dig up dirt on Mr. Biden, was a foreign policy debacle that resulted in his impeachment.

       While Mr. Trump would disagree that he has not produced outcomes, he might also say that the best ones will materialize in a second term. That is precisely what worries Mr. Edelman, who notes that the president has gradually ousted top national security officials who were willing and able to caution him about things like the perils of negotiating with North Korea.

       “In the first term, there were people who could warn him off agreeing to very, very bad deals,” Mr. Edelman said. “Now there’s almost nobody there who can tell him, ‘No, sir.’”