KIEV, Oct. 22 - Advanced radar systems being shipped to Ukraine to counter artillery strikes by pro-Russia separatists have been modified to prevent them from peering into Russia, The Wall Street Journal reported Thursday, citing U.S. officials.

The modifications drew fire from a leading Republican critic of the Obama administration, who called it a misguided attempt to mollify Russian President Vladimir Putin.

President Barack Obama signed an order on Sept. 29 to give Ukraine two radar systems worth $10 million each. U.S. officials said this week that the systems would arrive at Ukraine’s Yavoriv training ground by mid-November.

U.S. Army officials said they hope the radar would provide Ukraine with a new capability for stopping artillery and rocket attacks launched by separatists. Other officials said the transfer also would send a message to Kiev that Washington’s support for its security forces remains strong.

But with a cease-fire holding in eastern Ukraine and artillery attacks significantly reduced, the U.S. doesn’t want the equipment to antagonize Russia. The modifications are supposed to ensure that Ukrainian forces don’t escalate the current conflict by using the new systems to counter fire originating from Russian territory, officials said.

Sen. John McCain (R., Ariz.), chairman of the Senate Armed Services Committee, said the modifications to weaken the radar were symptomatic of a “delusional view” by the Obama administration that Mr. Putin will modify his behavior in Ukraine.

“This is part of their continuing effort to appease Vladimir Putin,” he said. “It sends a signal to Russia and Ukraine that we are not willing to seriously confront Vladimir Putin’s aggression.”

Republicans, and some Democrats, have been urging the Obama administration to provide more systems to Ukraine, including Javelin antitank missiles. The Obama administration has been unwilling to provide any equipment that could be construed as offensive weaponry.

Restrictions on the intelligence the U.S. has provided Ukraine have led to criticism in Congress and in Kiev. Satellite imagery provided by the U.S. typically only includes Ukrainian territory, obscuring activity and troop buildups on Russia’s side of the border.

Russian officials didn’t immediately reply to a request for comment. Moscow typically has been critical of American and allied support for Kiev. (wsj/ez)