KIEV, Ukraine -- Russian President Vladimir Putin backed a cease-fire in Ukraine declared by that country's new leader, calling for all sides to halt military activities even as he put more than 65,000 troops on combat alert.
Mr. Putin, while saying he supported the weeklong truce that Ukraine President Petro Poroshenko called for Friday, also said the move shouldn't be an ultimatum to militia groups and won't be "viable or realistic" without "constructive" steps toward negotiations on the disputes in the region.
His statement, issued late Saturday by the Kremlin, came after Russia ordered troops to take part in a drill in the wake of Mr. Poroshenko's move to quell violence in eastern Ukraine. The Russian drill is the biggest since the country annexed the Black Sea Crimean peninsula from Ukraine in March.
The U.S. has accused the government in Moscow of aiding pro-Russian separatists in Ukraine's eastern regions and last week imposed sanctions on people linked to the insurgency, adding to penalties announced more than a month ago. American and European officials have warned that more painful sanctions affecting Russia's access to financial markets, technology and military hardware may come as early as this week if Mr. Putin refuses to curb tensions.
U.S. analysts greeted Mr. Putin's support for the cease-fire with skepticism.
"The Russian side wants to avoid the imposition of further Western sanctions by saying that it supports a cease-fire, but you have to focus on Russian actions, not words," Angela Stent, director of the Center for Eurasian, Russian and East European Studies at Georgetown University in Washington, said in an email.
"As usual, Putin is trying to destabilize the situation in Ukraine and weaken the new government, while seeking to avoid sanctions from the West," said Robert Orttung, assistant director of the Institute for European, Russian and Eurasian studies at George Washington University, also in an email.
Russia had originally dismissed Ukraine's declaration of the cease-fire, spurring officials from the European Union and Germany Saturday to call on Mr. Putin -- before he issued his latest statement -- to support the peace plan.
Also before Mr. Putin's statement, Canadian Prime Minister Stephen Harper said his country would impose economic sanctions and travel bans against 11 people -- Vladimir Shamanov, the commander of the Russian Airborne Troops, and 10 Ukrainian militia and rebel government leaders. Feodosia Enterprise, a Crimea-based oil company, also is subject to the sanctions, Mr. Harper said.
Mr. Putin put troops in Russia's central military region on full combat alert and ordered them to take part in a test of military readiness that is to last through next Saturday and also will involve 5,500 pieces of military equipment, Vladimir Anikin, a spokesman for Russia's Defense Ministry, said by phone.
In Kiev, the Foreign Ministry denounced Russia's military activity, saying it "does not help to normalize the situation in Ukraine and to implement peaceful initiatives by the Ukrainian authorities," according to an emailed statement.
The statement was issued before Mr. Putin said he backed the cease-fire.
While Ukraine seeks a peaceful solution to the conflict, its military is ready to act "adequately" if the cease-fire is violated, Mr. Poroshenko said Saturday on his website prior to Mr. Putin's latest statement. The peace plan has "powerful support" from European and U.S. leaders, he said.
Ukraine called on all fighters to lay down arms, halting the offensive against rebels from 10 p.m. Friday until 10 a.m. next Friday, according to the president's website.
Pro-Russian militants expressed skepticism the truce will be implemented, as fighting continued in at least seven places. Those skirmishes left nine border troops and one Russian customs official wounded, and an unspecified number of militants killed, Ukrainian authorities said Saturday.