Russia-Ukraine updates: Putin says 'certain positive movements' in negotiations

The safety of the hundreds of staff who are still on duty at the Chernobyl Nuclear Power Plant is becoming more precarious, according to multiple agencies.

About 210 personnel have on duty since Feb. 24, the day before Russian military forces entered the disaster site, and have not rotated out, according to the agency.

Nuclear material and facilities demand continuous coverage, which requires employees to operate on a rotation, fixed, or modified shifts, according to a publication from the U.S. Department of Energy. There are many psychological and physiological impacts that can affect work performance, safety, and security without an organization, the material states.

Today, the State Nuclear Regulatory Inspectorate of Ukraine told the IAEA that it is becoming increasingly urgent and important for the safe management of the site to replace the current personnel.

While the staff has access to food, water and medicine to a limited extent, the situation is worsening, Ukraine’s nuclear regulator told the IAEA.

"I'm deeply concerned about the difficult and stressful situation facing staff at the Chornobyl nuclear power plant and the potential risks this entails for nuclear safety. I call on the forces in effective control of the site to urgently facilitate the safe rotation of personnel there," Rafael Mariano Grossi, Director General of the IAEA, said in a statement Tuesday.

Ukraine's nuclear regulator also asked the IAEA to lead the international support needed to prepare a plan for replacing the current team, which will include pausing the handling of nuclear material at the site, which includes decommissioned reactors as well as radioactive waste facilities

-ABC News' Christine Theodorou

Starbucks announced Tuesday it will immediately suspend all its operations in Russia, condemning the "horrific attacks on Ukraine by Russia."

"We continue to watch the tragic events unfold and, today, we have decided to suspend all business activity in Russia, including shipment of all Starbucks products," the company's chief executive officer, Kevin Johnson, said in a statement.

The company said its licensed partner agreed to immediately pause store operations and provide support for its nearly 2,000 workers.

"Through this dynamic situation, we will continue to make decisions that are true to our mission and values and communicate with transparency," Johnson said.

-ABC News' William Gretsky

McDonald's announced Tuesday it is temporarily closing its restaurants and pausing operations in Russia, as a result of the invasion of Ukraine.

"The conflict in Ukraine and the humanitarian crisis in Europe has caused unspeakable suffering to innocent people. As a System, we join the world in condemning aggression and violence and praying for peace," the company's chief executive officer, Chris Kempczinski, said in a statement.

McDonald's employs 62,000 people in Russia, operating in 850 communities, the company said. It will continue paying salaries for all its employees in Russia.

"Our values mean we cannot ignore the needless human suffering unfolding in Ukraine," said Kempczinski.

Kempczinski said it is impossible to predict when the company will be reopening its restaurants.

"We are experiencing disruptions to our supply chain along with other operational impacts. We will also closely monitor the humanitarian situation," Kempczinski said.

-ABC News' William Gretsky

Poland announced Tuesday it is "ready" to "immediately" hand over all its MiG-29 fighter jets to a U.S. air base in Germany to boost Ukraine's fight against Russia.

Ukrainian President Volodymyr Zelenskyy has asked the West and NATO to supply Ukraine with fighter jets.

The Polish government said in a statement that will provide its Russian-made MiGs to the Rammstein Air Base "free of charge," placing them "at the disposal" of the U.S. government, and asked the United States to backfill them "with used aircrafts with corresponding operational capabilities."

"The Polish Government also requests other NATO Allies -- owners of MiG-29 jets -- to act in the same vein," the statement added.

A senior U.S. defense official told ABC News: "We have seen the Polish government’s announcement and have nothing to offer at this time."

A spokesperson for the U.S. Department of State told ABC News they are working with the Polish government and consulting with NATO allies on this.

"This is Poland's sovereign decision to make. We have in no way opposed Poland transferring planes to Ukraine. There are a number of challenging practical question," the spokesperson said. "In the meantime, we continue to surge security assistance for Ukraine and deliveries are ongoing."

A senior U.S. diplomat told ABC News that the U.S. was not "pre-consulted" on this news. U.S. Under Secretary of State for Political Affairs Victoria Nuland told the Senate Foreign Relations Committee that she found out about Poland's announcement while driving to Capitol Hill to testify.

"To my knowledge, it wasn't pre-consulted with us that they plan to give these planes to us, but as you know, we have been having consultations with them for a couple of days now about this request from the Ukrainians to receive this aircraft, and, were they to donate them, whether we would be able to help support backfill in their own security need," Nuland said.

-ABC News' Christine Theodorou and Luis Martinez

Editor's note: This post was updated to reflect the correct fighter jet models as MiG-29s, not MiG-19s.