Prince William made a surprise visit this week to Poland, near the country's border with Ukraine, where he visited with British and Polish troops who are helping Ukraine fight against Russia. His trip was kept under wraps until he arrived, according to BBC News.

During his trip, he visited Rzeszow – about one hour from Ukraine – where he spoke to troops, thanking them for their work. "You're doing a really important job out here and defending our freedoms is really important, and everyone back home thoroughly supports you," he said, according to the BBC. 

He posted about his trip on social media Wednesday, and thanked Poland for helping Ukrainians fleeing the war-torn country find shelter.

He also highlighted a center for Ukrainian refugees that helps them learn Polish, provides food and supplies and also psychological and employment support. "It really is a sanctuary on the frontline of the humanitarian crisis," he tweeted.

Images taken during his visit show the prince, who is next in line to the British throne after his father, King Charles III, playing with children at the center, which houses around 300 Ukrainian women and children. He met with a boy, who showed the prince his art, and played ping-pong with a girl there.

On Thursday, he is expected to visit Polish President Andrzej Duda, according to the BBC. During his trip, he is set to visit the presidential palace, a refugee camp and Poland's Tomb of the Unknown Soldier, which is dedicated to those who died in war. 

The U.K. says it provided £2.3 billion ($2.8 million) in military assistance to Ukraine in 2022 and planned to match that this year. They are also aiming to train 10,000 Ukrainian troops in 120 days as well as training jet pilots. 

A small group of British personnel was deployed to aid in the training and Ukrainians were trained in the U.K. by the Royal Navy, the country's parliament said.

President Biden traveled to Ukraine last month, meeting with President Volodymyr Zelenskyy to discuss the United State's efforts to help Ukraine. The U.S. and its G7 partners and allies also announced sanctions against 200 people and entities that make revenue in Russia, and the Pentagon announced it would provide new unmanned aerial systems and counter-unmanned aerial systems to help Ukraine's fight against Russia. 

The Pentagon has also produced supplies for Ukraine and the U.S. has continually provided military aid like rockets, guns and ammunition to Ukraine since the early days of the war.

Polish Prime Minister Mateusz Morawiecki said last month that he spoke with Mr. Biden to increase the presence of U.S. troops in the country. 

Russian troops have been stationed at Ukraine's border with Poland and Belarus since the war began, and the prime minister told CBS News' "Face The Nation" that there is evidence Russia could attack other countries. 

"Yes, I do see lots of fingerprints of Russian forces, Russian services in Moldova," he said, adding that "this is a very weak, very weak country and we all need to help them."

Poland has also spent billions on housing, health care and other services as it hosts more than 1.5 million Ukrainian refugees. 

In:
• Prince William Duke of Cambridge
• War
• Ukraine
• The Royal Family
• Poland

Caitlin O'Kane is a digital content producer covering trending stories for CBS News and its good news brand, The Uplift.