Plaid Cymru's leader has defended visiting Ukraine "to show solidarity" as fears of a Russian invasion grow.
Adam Price said he was there in a personal capacity and had paid for the trip out of his own pocket.
Mr Price and Welsh Labour government minister Mick Antoniw MS arrived in the capital Kyiv on Saturday in spite of UK government advice not to travel.
Conservative MS James Evans said Senedd politicians had "no role to play in this matter".
Another Tory MS, the Vale of Clwyd's Gareth Davies, said the "dangerous trip" was "reckless", adding he hoped both men "get back to Wales safely, but please justify this on return".
Prime Minister Boris Johnson has said evidence suggests Russia is planning "the biggest war in Europe since 1945".
Less than 24 hours before the two men flew into the Ukrainian capital, US President Joe Biden said he was convinced Russian President Vladimir Putin had decided to launch an invasion which could start in the coming days, with Kyiv a potential key target.
The Foreign, Commonwealth and Development Office (FCDO) has advised against all travel to Ukraine and told all British nationals to leave.
In a further update on Saturday, the FCDO said: "British nationals should leave while commercial options remain.
"In the event of a military incursion, it is likely that commercial routes out of Ukraine will be severely disrupted and roads across Ukraine could be closed."
But Mr Price and Mr Antoniw, who comes from a Ukrainian family, are in the country for four days as part of a UK delegation, which also includes former Labour MEP Julie Ward and general secretary of the ASLEF union Mick Whelan.
During their stay they will meet Ukrainian workers, LGBTQ+ people, ethnic minorities and human rights defenders.
Following online criticism, Plaid leader Adam Price said on Twitter: "I felt I had a choice - to either comment from afar behind a phone or laptop, or come here to connect and understand on a human, meaningful level.
"I am obviously not here to solve the conflict, but I am here to show solidarity in a time where real, meaningful connection with real people means far more than a tweet, a press release or just another soundbite from a politician at home in their comfort zone.
"It's not going to be a good time to travel here for a long time and Senedd recess provided a window.
"If we want to see Wales truly connect with the world, then we must reach out in meaningful ways, even if that may feel uncomfortable at times."
On Saturday, Labour Pontypridd MS and Welsh government Counsel General Mick Antoniw said: "In too many of the discussions about the situation in Ukraine, it is the people themselves who are being bypassed.
"We want to listen to what the Ukrainian people say and to show our solidarity with them.
"We stand by them and their right to determine their own future and to defend their country from Russian aggression and imperialism."
Asked on the BBC Politics Wales programme how the Welsh government felt about a minister visiting Ukraine against foreign office advice, Social Justice Minister Jane Hutt MS said it was "a personal visit" for Mr Antoniw who has "very strong connections, obviously, family contacts in Ukraine".