The president told allied leaders that he would allow Ukrainian pilots to be trained on American-made F-16s, and is prepared to approve other countries’ transferring the jets to Ukraine.President Biden told U.S. allies on Friday that he would allow Ukrainian pilots to be trained on American-made F-16 fighter jets, several U.S. officials said, adding that the president is prepared to let other countries give F-16s to Ukraine — a major upgrade of the Ukrainian military and a sharp reversal.Since Russia launched its full-scale invasion of Ukraine 15 months ago, officials in Kyiv have pleaded for advanced warplanes to overcome Russian air superiority. But Mr. Biden has resisted, concerned that the jets could be used to hit targets deep inside Russia, and prompt the Kremlin to escalate the conflict. Pentagon officials have said that other weapons, especially air defenses, were needed more urgently, and the high cost of the F-16s could squeeze out other matériel.But several European countries that belong to the NATO alliance and have F-16s in their arsenals have called for an international effort to provide the training and transfer of their jets to Ukraine. Doing so would require American permission, because the weapons were first sold to them by the United States. Though not the most advanced U.S. fighter, the F-16 carries powerful radar that can spot targets from hundreds of miles away and modern missiles and other technology that American officials do not want duplicated or falling into hostile hands.Mr. Biden told other leaders of the Group of 7 nations, the world’s wealthiest democracies, of his decision on pilot training, opening a path to supplying Ukraine with fighter jets, at their summit meeting in Hiroshima, Japan, according to several officials who requested anonymity to speak candidly about sensitive deliberations.They said the United States and its allies would discuss in the coming months how to supply Kyiv with the jets themselves, and one senior administration official said the White House was prepared to approve that step. The United States is not expected, at least under current plans, to send its own F-16s.A group of F-16s flying over Washington, in March. Ukraine has said it needs the jets to compete effectively with Russia’s air force.Andrew Caballero-Reynolds/Agence France-Presse — Getty Images“I welcome the historic decision of the United States and @POTUS to support an international fighter jet coalition. This will greatly enhance our army in the sky,” President Volodymyr Zelensky of Ukraine, who is expected to address the Group of 7 this weekend, wrote on Twitter.In a joint statement, the allied leaders said they were committed “to continuing our security assistance to Ukraine as it defends itself against Russia’s aggression, tailoring our support to Ukraine’s needs.” The group vowed to provide “financial, humanitarian, military and diplomatic support Ukraine requires for as long as it takes.”Earlier on Friday, Mr. Zelensky had addressed an Arab League summit in Jeddah, Saudi Arabia, where he challenged the neutral stance many Arab countries have adopted on the war and implored them to help save Ukrainians “from the cages of Russian prisons.” “Unfortunately there are some in the world, and here among you, who turn a blind eye to those cages and illegal annexations,” he said. “I am here so that everyone can take an honest look, no matter how hard the Russians try to influence.”Western officials said Mr. Zelensky planned to travel to Hiroshima this weekend to attend the summit meeting. Ukrainian officials gave conflicting accounts, however, with some saying he would appear in person and others saying he would speak to the leaders by video link. The vagueness appears to reflect security concerns as Mr. Zelensky moves across the globe seeking aid and arms; he was in several European countries last week, as well as Saudi Arabia on Friday.Ukraine is expected to launch a major counteroffensive soon, hoping to retake more territory seized by Russia in the war’s early days. Any delivery of fighter jets would be months away, too late to affect that plan.The Group of 7 leaders in Hiroshima spent much of the day discussing the coming counteroffensive and its chances of forcing Russia to the negotiating table to discuss some form of an armistice that would stop the fighting, even if it did not resolve the central issues of the war.They are also poised to unveil a slew of new sanctions and export controls to clamp down further on the Kremlin’s ability to fund the war, and to crack down on third-party nations that have been secretly providing Russia with banned technologies that can be used in weapons systems.Earlier on Friday, President Volodymyr Zelensky of Ukraine told a gathering of the Arab League not to “turn a blind eye” to the atrocities committed by the Russian forces.Saudi Press Agency/EPA, via ShutterstockThe allies appear determined to demonstrate unified resolve to support Ukraine at a time when President Vladimir V. Putin of Russia seems to be betting that their interest and commitment will wane.Mr. Biden’s changed stance on F-16s is his latest about-face on allowing Ukraine to field advanced weapons, including HIMARS rocket launchers, Patriot air defense missile systems and Abrams tanks. In each case, the president at first refused, only to change his mind under pressure from European allies.Top Pentagon officials have consistently said that they do not believe Ukraine needs F-16s at this stage of the conflict.Celeste A. Wallander, the assistant secretary of defense for international security affairs, told the House Armed Services Committee last month that advanced Western fighter aircraft ranked only “about eighth” on Ukraine’s priority list. She said officials have focused on resources with the “highest priority capabilities, and that has been air defense, artillery and armor.”But the push for F-16s by Ukraine and its supporters in Congress was reinforced this week when Yahoo News reported that an internal U.S. Air Force assessment concluded it would take only four months to train Ukrainian pilots to operate the fighters, a far shorter time frame than Pentagon officials had cited previously.The document, which a senior Air Force official confirmed and said was shared with several NATO allies who fly F-16s, contained a detailed assessment undertaken in late February and early March at Morris Air National Guard Base in Tucson, Ariz. Two Ukrainian pilots were given “no formal training” on the F-16, according to the assessment, other than a brief familiarization, and then were tested on a flight simulator for several hours.A Ukrainian soldier passes a crater caused by Russian bombardment in the village of Heorhiivka in eastern Ukraine. Kyiv says F-16s would greatly increase their forces’ ability to defend against aerial attacks.Finbarr O’Reilly for The New York TimesAn appearance by Mr. Zelensky at the Group of 7 would be a strong rebuff to Mr. Putin and a reminder of how thoroughly relations with Russia have deteriorated. Thirty years ago, President Clinton met with Boris Yeltsin, then the president of Russia, in Japan to begin to map the integration of a post-Soviet Russia into the world economy, as Mr. Clinton promised to seek the repeal of Cold War sanctions. Five years later, Russia joined what became the Group of 8.Now all that has been reversed. After Russia annexed Crimea in 2014, it was suspended from the group, and left it entirely three years later. Russia’s economy is struggling under sanctions imposed since the invasion last year, particularly the price cap on its oil sales, and more are coming.Britain on Friday said it was implementing a ban on Russian diamonds, copper, aluminum and nickel. Australia also said on Friday it was imposing new financial sanctions targeting 21 entities and three individuals, including Russia’s largest gold company, petroleum and steel companies and defense entities.The United States also rolled out a “substantial package” of restrictions, including cutting off 70 more firms from American exports and adding more than 200 individuals and entities to its sanctions list. The measures are meant to crack down on people or companies that are helping Moscow to evade existing sanctions.The fresh round of penalties “will further tighten the vise on Putin’s ability to wage his barbaric invasion and will advance our global efforts to cut off Russian attempts to evade sanctions,” Treasury Secretary Janet L. Yellen said in a statement on Friday.Until now, the Ukraine war has seemed far away from daily life in Moscow, but Russian leaders are growing increasingly nervous about the repercussions of a promised Ukrainian counteroffensive.Natalia Kolesnikova/Agence France-Presse — Getty ImagesThe United States will broaden sanctions to cover more corners of the Russian economy, striking at its avenues to acquire semiconductors and other high-tech goods from Group of 7 nations, which American officials said Friday are critical to Russia’s ability to build weapons. Antony J. Blinken, the secretary of state, said in a release that the new sanctions would take aim at components Russia needs to build a drone that is currently being deployed in Ukraine.The new penalties also seek to squeeze Russia’s ability to drill for oil and gas, and to crimp venture capitalists and financial services firms that American officials said were aiding sanctioned Russian businesses.Goods that Western businesses are now prohibited from selling to Russian buyers often reach them through middlemen — changing hands, legal jurisdictions and free-trade zones multiple times. The trade is hard to track and harder to enforce, especially for “dual use” goods that have both civilian and military applications.With many of Russia’s other revenue streams squeezed by previous rounds of sanctions, officials have homed in on diamonds as a lucrative trade still providing Moscow with funding for its war. Russia is the world’s largest supplier of small diamonds, exporting more than $4.5 billion in 2021, making the gem its top non-energy export by value. More