The White House was on the defensive Wednesday as criticism mounted that President Biden should be doing more to help Ukraine fend off Russia’s invasion.

Hours after Ukrainian President Volodymyr Zelenskyy electrified a joint session of Congress with a virtual plea for more U.S. military help, a graphic video of his country’s suffering, and soaring rhetoric that invoked the Rev. Martin Luther King Jr., Pearl Harbor and the Sept. 11, 2001, attacks, Mr. Biden sought to counter complaints that he has been too weak on Russia by escalating his rhetoric and announcing an additional $800 million in security assistance to Ukraine.

Perhaps reflecting the pressure to present a tougher front, Mr. Biden for the first time explicitly called Russian President Vladimir Putin a “war criminal.” He made the remark to a reporter as he left the White House event announcing the package of long-range anti-aircraft systems, small arms, ammunition and high-tech drones. A Kremlin spokesman quickly denounced the president’s language as “unacceptable and unforgivable rhetoric.”

White House press secretary Jen Psaki said later that the president was “speaking from his heart” when he made the remarks about Mr. Putin but added that there is a legal process for determining war crimes.

“We’ve all seen barbaric acts, horrific acts by a foreign dictator in a country that is threatening and taking the lives of civilians, impacting hospitals, women who are pregnant, journalists and others,” she said.

The back-and-forth came on a day when Russian forces fatally shot 10 civilians standing in line for bread in the besieged city of Chernihiv, Russian artillery bombed a theater where Ukrainian civilians were reportedly sheltering in the port city of Mariupol, the capital Kyiv faced a fresh round of shelling from nearby Russian forces, and NATO Secretary-General Jens Stoltenberg said the alliance is considering adding “substantially more forces” to its eastern flank in light of the escalating Russian operation in Ukraine.

Pentagon officials said they have seen “increased naval activity” in the south near the key port of Odessa, including vessels identified as tank landing ships that could be used in an amphibious assault. Like most of the country’s other major cities, Odessa remains in Ukrainian hands three weeks after the Russian invasion.

“It could be to prepare the way for a ground assault,” a senior Defense Department official said in a background briefing. “We would not be surprised to see them interested in Odessa, given its strategic location.”

Capturing Odessa would put Moscow a giant step closer to closing off Ukraine’s access to the Black Sea. Russian troops have been fought to a standstill by the much-smaller Ukrainian military. On Monday, however, they were largely unopposed while landing at a spot on the Sea of Azov.

Russia has fired more than 980 missiles since the invasion, U.S. officials estimate. But Mr. Putin’s decision to invade is coming at an ever-higher price. Moscow has poured about 75% of its ground combat units into the fight, and the casualties have been staggering, officials said.

“Every day, they are experiencing losses of equipment, aircraft and people,” the Pentagon official said. “We’ve definitely seen them have discussions about what they might need to do to resupply — and that includes manpower.”

Separately, Ukrainian and Russian negotiators held a third straight day of direct talks. The head of the Russian delegation said Moscow is weighing a diplomatic compromise under which Ukraine could become an officially neutral country with its own military, along the lines of Sweden or Austria. Vladimir Medinsky, Moscow’s top negotiator, said the preservation of Ukraine’s neutral status and the size of its military are the topics under consideration.

Mr. Zelenskyy’s government has apparently rejected Russia’s proposal of a Findlandization of Ukraine. Mykhailo Podolyak, Ukraine’s top negotiator, said any talks to end fighting should focus on security guarantees instead, according to the English-language Moscow Times newspaper.

“Ukraine is now in a direct state of war with Russia. Consequently, the model can only be ‘Ukrainian’ and only on legally verified security guarantees,” Mr. Podolyak said, the Moscow Times reported.

White House frustration

The administration’s frustration with the criticism of Mr. Biden’s performance was on full display at a combative daily press briefing, where Ms. Psaki vigorously insisted the White House has not pulled its punches against Russia or failed to give Mr. Zelenskyy and his embattled government what they say they need to prevent a Russian takeover.

“We have done more economic sanctions and put in place more financial consequences than we have in any circumstance ever in the world,” she told reporters. “So I wouldn’t say that is holding back in any capacity.”

Including the aid announced Wednesday, the Biden administration said it has provided more than $1 billion in military and other support to Ukraine this week and more than $2 billion since the crisis began.

The U.S. support “is about making sure Ukraine will never be a victory for Putin, no matter what advances he makes on the battlefield,” Mr. Biden said in his address.

The U.S. package of military assistance will include anti-tank missiles and more of the portable air defenses that the U.S. has already provided to Ukraine, including Javelin and Stinger missiles.

Still, Mr. Biden stopped short of granting all of Mr. Zelenskyy’s requests. The U.S. and NATO continue to reject any idea of enforcing a no-fly zone over Ukraine or sending used MiG fighter jets to bolster Ukraine’s air defenses. They say the move would provoke Mr. Putin and risk a direct war between Russian and NATO forces.

Mr. Zelenskyy appealed again for the U.S. and its allies to provide air cover. Sviatoslav Yurash, a member of Ukraine’s parliament, said a no-fly zone over Ukraine is his country’s most significant need. U.S. officials estimate Russia is flying some 200 sorties over Ukraine daily, compared with just five to 10 for the outmatched Ukrainian air forces.

“Our essential request is a no-fly zone because Russia is using its overwhelming air force to cause havoc and destruction in our country,” Mr. Yurash told The Washington Times in a phone interview. “It is our unyielding request time and time again.”

“The big thing we keep repeating is the no-fly zone because of the reality of Russian air power,” he said. “They are using it to kill Ukraine citizens in numbers we haven’t seen since the Second World War.”

It’s not clear whether the moves Wednesday will satisfy Mr. Biden’s critics on Capitol Hill. Republicans portrayed Mr. Biden as a step behind on Ukraine and accused him of being too slow to take on Mr. Putin.

“President Biden needs to step up his game right now before it’s too late,” Senate Minority Leader Mitch McConnell, Kentucky Republican, told reporters. “I think comparing Zelenskyy to Biden is depressing. We’re not doing nearly enough quickly enough to help the Ukrainians.”

Mr. McConnell said the administration has “discouraged” NATO countries from taking more aggressive action in Ukraine.

Mr. Biden is hearing calls from within his own party to do more to assist Ukraine. Sen. Jeanne Shaheen, New Hampshire Democrat, last week urged Mr. Biden not to stand in the way of a Polish proposal to ship its MiG fighter jets to Kyiv via a U.S. air base in Germany for transshipment on to Kyiv.

Ms. Psaki was peppered with questions about the level of support for Ukraine. She bristled as reporters grilled her on the decision to nix the Polish offer. At one point, she snapped, “We’ve spoken to that approximately 167 times.”

• Dave Boyer contributed to this article, which is based in part on wire service reports.

Russian warships are shelling towns on the outskirts of Odesa, a major port city on the Black Sea, in the latest military campaign in Moscow’s three-week-old invasion of Ukraine.

Pentagon officials on Wednesday said they have seen “increased naval activity” in the area, including vessels identified as tank landing ships that could be used in an amphibious assault.

A senior Defense Department official didn’t know why the Russians were firing on suburbs of Odesa rather than the city itself. 

“It could be to prepare the way for a ground assault,” he said. “We would not be surprised to see them interested in Odesa, given its strategic location.”

Capturing Odesa would put Moscow a giant step closer to closing off Ukraine’s access to the Black Sea. Russian troops have been fought to a standstill by the much-smaller Ukrainian military. But on Monday, they were largely unopposed while landing at a spot on the Sea of Azov.

It wasn’t clear if Russia will use amphibious forces currently on ships on the Black Sea or other troops that have already landed if military commanders decide to move on Odesa, Pentagon officials said.

Russia has fired more than 980 missiles — of all varieties — since the invasion. President Vladimir Putin’s decision to attack its much smaller neighbor has come at a high cost. Moscow has poured about 75% of its ground combat units in the entire country into the fight and the casualties have been staggering, officials said.

“Every day they are experiencing losses of equipment, aircraft, and people,” the official said. “We’ve definitely seen them have discussions about what they might need to do to resupply — and that includes manpower.”

Pentagon officials confirmed the stepped-up Russian naval activity in the Black Sea as the White House released a list of $800 million worth of military hardware soon to be heading to Ukraine, ranging from 2,000 Javelin anti-tank weapons to 70 Humvees and more than 20 million rounds of small ammo.

“We’re also talking to allies and partners about providing the Ukrainians with some systems that they know how to use. That includes air defense systems,” the official said.

Critics of a revived nuclear deal with Iran say Russia is actively exploiting the Biden administration‘s ardent desire to clinch a deal, using the war in Ukraine in part to distract the world from Tehran’s illicit nuclear weapons activities and to secure major sanctions relief for the Iranian regime.

Negotiators for the U.S., Iran, Russia, China, Germany, Britain and France are widely believed to be in the final stages of a potential revival of the 2015 nuclear deal, negotiated by President Obama and repudiated three years later by President Trump. The deal broadly would lift many punishing U.S. sanctions imposed on Iran‘s economy and its trading partners after Mr. Trump withdrew in exchange for reinstated curbs on Tehran’s suspect nuclear programs.

While the talks have stalled in recent days over last-minute demands from Moscow, the top Democrat on the Senate Foreign Relations Committee said Wednesday that he believes Russia and Iran are conspiring to get new concessions from Mr. Biden and his negotiating team.

“Iran is simply looking for any excuse to drag out talks while it continues to advance its dangerous nuclear program,” Sen. Robert Menendez, New Jersey Democrat, told a virtual gathering of lawmakers organized Wednesday by the Iranian dissent-led Organization of Iranian American Communities (OIAC). He said Tehran’s refusal to condemn Russia‘s invasion of Ukraine is telling.

“The Iranian regime remains one of the few countries to vocally back Russia‘s completely unprovoked and devastating invasion of Ukraine,” he said, adding that “Russia is now leveraging its role in the talks in Vienna to again redirect attention away from the very real and immediate threat of Iran‘s nuclear program.”

In an unusual twist of bipartisanship, Mr. Menendez’s assertions dovetailed with comments by Sen. Ted Cruz, Texas Republican, who warned the Biden administration is falling into a trap set by Moscow and Tehran to extract sanctions relief from Washington.

“President Joe Biden wants nothing more than to create a new nuclear agreement with the Iranian regime that is even weaker than the catastrophic 2015 deal, even if it means surrendering to both [Iranian Supreme Leader Ayatollah Ali Khamenei] and [Russian President] Vladimir Putin,” Mr. Cruz told the OIAC event Wednesday.

“The Biden administration wants to sanction Putin on the one hand, while simultaneously giving him a financial lifeline through an Iran deal on the other,” said Mr. Cruz, who added that “Republicans will block the terrible deal and the next Republican president will tear up whatever’s left of it on Day One in 2025.”

The agreement known as the Joint Comprehensive Plan of Action (JCPOA) has been in disarray since 2018 when Mr. Trump pulled the U.S. out of it. Critics said the original deal had included too many loopholes and did nothing to constrain Iran‘s ballistic missile programs or its support for anti-U.S. and anti-Israel allies around the Middle East.  

The Biden administration has pushed for months to restore the agreement and the announcement of a breakthrough and a slacking of sanctions seemed imminent last week. But the push has stalled during recent days amid blowback from the Ukraine crisis, with Russia — one of the many parties of the original 2015 deal — introducing new demands that have appeared to derail the talks.

U.S. officials claimed Moscow was threatening to block the restoration of the deal unless the Biden administration guaranteed that recent sanctions imposed on Russia over its invasion of Ukraine won’t prevent Russian firms from engaging in future nuclear-related trade with Iran, once JCPOA sanctions on Tehran are lifted.

According to Reuters, Russian Foreign Minister Sergey Lavrov claimed Tuesday that Russia‘s objections have been met. Mr. Lavrov made the announcement after meeting Tuesday with Iranian Foreign Minister Hossein Amirabdollahian in Moscow.

The Biden administration has offered little clarity on the issue. State Department spokesman Ned Price told reporters on Tuesday that the “JCPOA is not going to be an escape hatch for the Russian Federation and the sanctions that have been imposed on it because of the war in Ukraine.”

At the same time, however, Mr. Price said that the administration “of course, would not sanction Russian participation in nuclear projects that are part of resuming full implementation of the JCPOA.”

“We can’t and we won’t and we have not provided assurances beyond that to Russia,” he said.  

The hedged diplomatic rhetoric appeared only to harden bipartisan concerns in Congress. Mr. Menendez said he has personally “been outspoken about the threat of a nuclear armed Iran and have expressed serious concerns about the talks in Vienna to revive the deeply flawed JCPOA.”

By contrast, Mr. Amirabdollahian tweeted this week he was reassured by the “productive” meeting with Mr. Lavrov.

“Reassured that Russia remains onboard for the final agreement in Vienna,” he wrote. “More than ever, ball is in U.S. court to provide the responses needed for successful conclusion of the talks.”