Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty in speech denouncing West

A high-stakes mission from the United Nations' nuclear watchdog reached a Russian-controlled power plant in Ukraine on Thursday afternoon amid reports of heavy fighting there.

The International Atomic Energy Agency has long sought access to the Zaporizhzhia nuclear power plant, Europe's largest, since invading Russian troops overran the site and the surrounding town of Enerhodar in southeastern Ukraine in early March. The Ukrainian workers have been left in place to keep the plant operating, as it supplies electricity across the war-torn country, but the site is now on the frontline between Russian-occupied and Ukrainian-controlled territory. Moscow and Kyiv have traded accusations of shelling at or near the plant in recent days and weeks, fueling fears that the conflict could spark a radiation disaster.

IAEA Rafael Grossi, who is leading a team of over a dozen experts sent to inspect the besieged plant, said earlier Thursday that they were "aware" of the high risk posed by the "increased military activity in the area" between Russian and Ukrainian forces.

"There has been increased military activity, including this morning, until very recently, a few minutes ago. I have been briefed by the Ukrainian regional military commander here about that and the inherent risks," Grossi told reporters as he and his team left their hotel in the city of Zaporizhzhia, north of Enerhodar, across the Dnipro River.

"But, weighing the pros and cons, and having come so far, we are not stopping," he added. "We are moving now."

A few hours later, the IAEA announced via Twitter that its "Support and Assistance Mission ... has just arrived at Zaporizhzhya Nuclear Power Plant to conduct indispensable nuclear safety and security and safeguards activities."

A long-awaited expert mission from the United Nations' nuclear watchdog arrived in the southeastern Ukrainian city of Zaporizhzhia on Wednesday.

The International Atomic Energy Agency's team will travel to the Zaporizhzhia nuclear power plant near the town of Enerhodar on Thursday for the first time.

IAEA Director General Rafael Grossi, who is leading the mission, told reporters during a press briefing in Zaporizhzhia on Wednesday that the aim is for his team to establish a permanent presence at the Russian-occupied plant and that the initial phase would take "days."

When asked if it was possible to demilitarize the site, Grossi said it was "a matter of political will" and that his mission is to preserve Europe's biggest nuclear power plant. He admitted it was "not a risk-free mission" and underlined that his team would be operating in Ukrainian sovereign territory but in cooperation with Russian forces.

Asked if he thought Russian troops would really give his team full access, Grossi told reporters the IAEA was on a "technical mission" and that he was confident his team could work "on both sides."

-ABC News' Tom Soufi Burridge

Secretary of State Antony Blinken on Tuesday celebrated the first shipment of Ukrainian grain to arrive in the Horn of Africa -- a region facing dire hunger -- since Russia’s invasion began.

"The United States welcomes the arrival in Djibouti of 23,300 metric tons of Ukrainian grain aboard the ship Brave Commander. This grain will be distributed within Ethiopia and Somalia, countries that are dangerously food insecure after four years of drought," Blinken said in a statement.

This is the first shipload to reach the region since a United Nations-brokered deal that allowed ships to leave Ukraine’s ports again.

According to Ukrainian officials, dozens of ships have been able to safely navigate the Black Sea in recent weeks. But State Department officials have claimed Russian allies, like Syria, have unfairly benefitted from recent exports, proving detrimental to countries the World Food Programme has determined are facing a greater level of need.

-ABC News' Shannon Crawford

The European Commission said it received a request from the Ukrainian government on Friday for potassium iodide tablets as a preventative safety measure to increase the level of protection around the Zaporizhzhia nuclear power plant. The European Response Coordination Centre quickly mobilized 5.5 million potassium iodide tablets through the EU Civil Protection Mechanism for Ukraine, including 5 million from the rescEU emergency reserves and 500,000 from Austria.

“No nuclear power plant should ever be used as a war theatre," EU Commissioner for Crisis Management Janez Lenarčič said. "It is unacceptable that civilian lives are put in danger. All military action around the Zaporizhzhia nuclear power plant must stop immediately."

-ABC News' Max Uzol