WASHINGTON (AP) — President Joe Biden has given Ukraine the go-ahead to use American weaponry to strike inside Russia for the limited purpose of defending Kharkiv, according to four U.S. officials familiar with the matter.

The officials, who requested anonymity to discuss the sensitive matter, underscored that the U.S. policy calling on Ukraine not to use American-provided ATACMS or long-range missiles and other munitions to strike offensively inside Russia has not changed.

Biden's directive allows for U.S.-supplied weapons to be used for "counterfire purposes in the Kharkiv region so Ukraine can hit back against Russian forces that are attacking them or preparing to attack them," one official said.

Ukrainian officials have stepped up calls on the U.S. administration to allow their forces to defend themselves against attacks originating from Russian territory. Kharkiv, Ukraine's second-largest city, is just 20 kilometers (12 miles) from the Russian border.

Biden's decision was first reported by Politico.

Ukrainian officials, most notably Ukrainian President Volodymyr Zelenskyy, have been increasingly vocal in arguing that the restriction was putting Ukrainian forces in an untenable situation as Russia intensified attacks around the northeast Kharkiv region.

The advances came with Russia exploiting a lengthy delay in replenishment of U.S. military aid and as Western Europe's inadequate military production has slowed crucial deliveries to the battlefield for Ukraine.

Talks about changing the policy intensified inside the Biden administration more than two weeks ago, after Russia stepped up its offensive around Kharkiv, according to one of the officials familiar with the White House deliberations.

Defense Secretary Lloyd Austin, White House national security adviser Jake Sullivan and Gen. CQ Brown, chairman of the Joint Chiefs of Staff, held a secure video conference with their Ukrainian counterparts in which the Ukrainian side pressed for permission to use U.S. weaponry to hit Russian positions across the border that were being used to attack the Kharkiv region, according to a U.S. official familiar with the White House deliberation.

Following that May 13 meeting with the Ukrainians, Sullivan, Austin and Brown huddled and agree to make a recommendation to Biden to alter the policy.

Sullivan presented the recommendation to Biden two days later, making the case that it was common-sense for the Ukrainians to be able to strike back to counter the attacks on their land that were originating from Russian territory. Biden agreed.

Later on May 15, Biden had a follow-up conversation with Gen. Christopher Cavoli, who leads U.S. European command, Austin and Sullivan and asked them to move forward on finalizing the details to the change in policy.

Meanwhile, during Secretary of State Antony Blinken's visit to Kyiv two weeks ago, Zelenskyy made his case for using American weapons to strike back at positions in Russia that were launching attacks into north and northeast Ukraine.

Blinken was convinced and brought that message back to Washington, according to three U.S. officials familiar with the top U.S. diplomat's thinking.

Blinken met with Biden and Sullivan on May 17, following his visit to Kyiv, and shared what he heard from Zelenskyy and made clear that he also supported giving the Ukrainians more leeway to strike back on Russia.

Still, Biden remained cautious and asked for due diligence before giving final approval.

Sullivan convened the administration's national security leaders for a conversation the following week, and they all agreed to move forward. Sullivan received final approval from Biden several days ago, but the guidance did not go into effect until Thursday, the official said.

It wasn't an easy decision to make. Since the start of the Russian invasion in February 2022, Biden has been steadfast in his opposition to Ukraine's offensive use of American-made weaponry, concerned that the action could be seen as provocative and lead to Moscow widening the war.

Blinken said in Moldova on Wednesday that U.S. policy on how Ukraine deploys American weapons is constantly evolving, hinting that Washington may alter its unwritten prohibition on Ukraine's use of them for attacks on Russian territory. On Thursday, Blinken joined NATO foreign ministers for a meeting in Prague, where during a tour of a Czech military base he saw armored vehicles that are being sent to Kyiv.

Although U.S. officials insist there is no formal arms ban, they have long made clear that they believe the use of American weapons to attack targets inside Russia could provoke an escalatory response from Moscow, something that Russian President Vladimir Putin has promised.

That position, Blinken noted, was a "hallmark" of the Biden administration's stance on Ukraine to "adapt and adjust" as needed.

"As the conditions have changed, as the battlefield has changed, as what Russia does has changed in terms of how it's pursuing its aggression, escalation, we've adapted and adjusted, too, and I'm confident we'll continue to do that," Blinken said at a news conference in Moldova.

"We're always listening, we're always learning, and we're always making determinations about what's necessary to make sure that Ukraine can effectively continue to defend itself, and we'll continue to do that," he said.

Calls for a change in policy have been mounting.

Earlier this week, French President Emmanuel Macron and NATO chief Jens Stoltenberg said that Western countries should not object if Ukraine needs to strike inside Russia to defend itself. Stoltenberg reaffirmed that position on Thursday.

"I believe that time has come to (re)consider some of these restrictions to enable the Ukrainians to really defend themselves," he said. "We need to remember what it is. This is a war of aggression launched by choice by Moscow against Ukraine."

The right to self-defense, he said, " includes also striking legitimate military targets outside Ukraine."

Czech Foreign Minister Jan Lipavsky said at a NATO-related event Thursday in Prague that Ukraine needs resources to counter Russia's relentless assault.

"Ukraine cannot fight against Russia with one hand tied behind its back," he said. "Ukraine must be able to fight against Russia's barbaric invasion even on Russian territory. Political resolve must be backed by credible capabilities."

Norway's foreign minister, Espen Barth Eide, told Norwegian broadcaster NRK that his country believes Ukraine "has a crystal-clear right under international law to attack Russia inside Russia as part of the defense of its territory."

Biden's decision comes as he's set to travel to France early next month to attend D-Day 80th anniversary commemorations in Normandy, a watershed moment in changing the course of World War II. Zelenskyy is among dozens of world leaders expected to attend the D-Day commemorations.

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Lee reported from Prague. Associated Press writers Karel Janicek in Prague and Ellen Knickmeyer contributed to this report.