Russia invades Ukraine

Hundreds of Ukrainians fleeing Russia's invasion of their country have arrived at the Mexican border city of Tijuana to seek US asylum and more are expected, a Tijuana city official and a volunteer told CNN on Saturday.

Enrique Lucero, director of migrant affairs for the city of Tijuana, said there were around 1,500 Ukrainians in the city currently and he expected the number to increase to 2,000 by the day's end.

Lucero said he expects all the migrants to enter the United States, but said American authorities have been slow to process them. The city was working to convert a sports facility into a temporary shelter to house all the incoming arrivals, Lucero told CNN.

Inna Levien, an Orange County, California resident who belongs to a group that is spearheading a volunteer effort to assist Ukrainians gathered near the border, told CNN that the number of Ukrainians has quadrupled in the past three days.

Once the migrants arrive at the border, Levien's group puts them on a list and assigns them a number, that way they don't have to wait in line the entire time for entry. She said the wait to get across can take more than 24 hours.

The city of Tijuana has been instrumental in providing relief, Levien said. A bus stop was recently converted by the city into a temporary shelter while a network of churches has sprung to help house families as they wait for their turn to be processed, Levien added.

CNN has reached out to the State Department and US Customs and Border Protection but did not receive a response Saturday.

Some context: The Department of Homeland Security is allowing Ukrainians, on a case-by-case basis, to be exempted from Trump-era pandemic restrictions on the US-Mexico border. Those restrictions will end on May 23, the US Centers for Disease Control and Prevention announced Friday. The US will welcome up to 100,000 Ukrainian refugees and others fleeing Russia’s aggression, the Biden administration announced last month.

CNN’s Priscilla Alvarez contributed to this report.

In the early morning hours on Sunday in Ukraine, these are the latest developments in the war:

Russia shifting focus to victory by early May in eastern Ukraine, US officials say: Russia has revised its Ukraine war strategy to focus on taking control of the Donbas and other regions in eastern Ukraine with a target date of early May, according to several US officials familiar with the latest US intelligence assessments. 

More than a month into the war, Russian ground forces have been unable to keep control of areas where they have been fighting. 

May 9 is a prominent holiday on the Russian calendar, a day on which the country marks the Nazi surrender in World War II with a huge parade of troops and weaponry across Red Square in front of the Kremlin. The officials say Putin wants to celebrate a victory of some kind in his war that day. 

Ukrainian negotiator claims advances in talks with Russia, possibility of 'direct consultations' between Zelensky, Putin in future: David Arakhamia, a member of the Ukrainian negotiating team in talks with Russia, said the Russian side has responded positively to Ukrainian positions on several issues.

Arakhamia said there is a possibility of "direct consultations" between Ukrainian President Volodymyr Zelensky and Russian President Vladimir Putin, something he said had been facilitated in part by Turkish President Recep Tayyip Erdogan. 

The Ukrainian side said there had been agreement to suspend negotiations on the status of Crimea for 15 years, but the Russian side has not confirmed, and the Kremlin has publicly reiterated its position Crimea is part of Russia.

Dmytro Kuleba, Ukraine’s foreign minister, said there was no official confirmation of those positions in writing, according to Arakhamia.

However, Arakhamia added: "Orally, as of yesterday, in a video conference, we heard that the Russian side does not object to such [Ukrainian] positions."

David Arakhamia, a member of the Ukrainian negotiating team in talks with Russia, said the Russian side has responded positively to Ukrainian positions on several issues and there is a possibility of "direct consultations" between Ukrainian President Volodymyr Zelensky and Russian President Vladimir Putin, something he said had been facilitated in part by Turkish President Recep Tayyip Erdogan. 

Ukrainian officials have outlined their vision of a roadmap to a potential truce, which would include possible neutral status for Ukraine backed by a broad alliance of security guarantors.

The status of Crimea -- annexed by Russia from Ukraine in 2014 -- has been a sticking point in potential negotiations between Ukraine and Russia. Ukraine and most of the international community consider the peninsula to be illegally occupied. The Kremlin consistently says the status of Crimea is settled. 

The Ukrainian side said there had been agreement to suspend negotiations on the status of Crimea for 15 years, but the Russian side has not confirmed, and the Kremlin has publicly reiterated its position Crimea is part of Russia.

Dmytro Kuleba, Ukraine’s foreign minister, said there was no official confirmation of those positions in writing, according to Arakhamia.

However, Arakhamia added: "Orally, as of yesterday, in a video conference, we heard that the Russian side does not object to such [Ukrainian] positions."

The possibility of a role for China as a potential security guarantor for Ukraine appears to be credible, according to Arakhamia. 

Russia has revised its Ukraine war strategy to focus on taking control of the Donbas and other regions in eastern Ukraine with a target date of early May, according to several US officials familiar with the latest US intelligence assessments. 

More than a month into the war, Russian ground forces have been unable to keep control of areas where they have been fighting.

Russian President Vladimir Putin is under pressure to demonstrate he can show a victory, and eastern Ukraine is where he is most likely to achieve that, officials say. US intelligence intercepts suggest Putin is focused on May 9, Russia’s “Victory Day,” according to a US official.

May 9 is a prominent holiday on the Russian calendar, a day on which the country marks the Nazi surrender in World War II with a huge parade of troops and weaponry across Red Square in front of the Kremlin. The officials say Putin wants to celebrate a victory of some kind in his war that day. 

But other officials note even if there is a Russian celebration, an actual victory may be further off. 

Still, US and European officials say any deadlines Moscow may set rhetorically don’t change the reality on the ground that Russia appears to be preparing for the prospect of an extended conflict.

A European diplomat said while the Kremlin is talking optimistically, Putin is preparing for a “Chechnya-style long, drawn-out war, because he, to a certain extent, has nowhere else to go on this.”

There are several reasons behind the May timeframe, the officials say. As the winter freeze ends and the ground softens, it will be harder for heavy Russian ground units to maneuver, meaning it’s vital for those forces to get into place as soon as possible, US intelligence assesses. 

Russian-backed fighters have also already been in that region for years. The Donbas region of Eastern Ukraine is where Russian separatist forces took control of territory in 2014.

Former Ukrainian Prime Minister Arseniy Yatsenyuk told CNN’s Wolf Blitzer Friday the Ukrainians believe they are facing a “very complex and difficult month” as Putin tries meet a deadline.

The US also assesses Putin is now preparing, for the first time, to name an overall commander of the war to achieve greater Russian successes, two US officials said. The US believes Putin will likely name a general who has been in the southern part of Ukraine because that is a place where Russians have succeeded in their objectives.

As Sunday approaches in Ukraine, catch up on the latest developments here.

Russians move out of Kyiv region as officials look to the east: Ukraine's deputy defense minister said Saturday the Kyiv region had been "liberated" from Russian forces. Meanwhile, Ukrainian presidential adviser Oleksiy Arestovych said heavy fighting is still expected in the east of Ukraine, near Mariupol, and in the country's south. He warned that the military effort "will not be easy" in those regions. 

Further evacuations: More than 4,000 civilians were evacuated through corridors in Ukraine on Saturday, according to the country's deputy prime minister, including over 2,000 people for the besieged port city of Mariupol.

The International Committee for the Red Cross team that departed Zaporizhzhia on Saturday morning as part of renewed attempt to reach Mariupol have yet to reach the city, an ICRC spokesperson told CNN.

US to facilitate tanks transfer: The US is expected to help facilitate the transfer of Soviet-era tanks "within days" to Ukraine, according to a source familiar with the plan.

Ukrainian presidential adviser Mykhailo Podolyak earlier on Saturday called on the US and its allies to deliver heavier weaponry to Ukraine as the Russian military shifts its campaign focus. 

Gas keeps flowing: Russian gas continues to enter Germany despite Russian President Vladimir Putin's ultimatum on Thursday for "unfriendly" nations to pay for their energy in rubles starting Friday or risk being cut off from vital supplies. Kremlin spokesperson Dmitry Peskov said Friday that Russia would not turn off gas supplies to Europe immediately.

"Deliveries are incoming. Supply security is still guaranteed," a German government spokesperson told CNN.

Hanna Maliar, Ukraine's deputy defense minister, said Saturday that the Kyiv region had been "liberated" from Russian forces.

She said in a post on Facebook that Bucha, Irpin, Hostomel and "the whole Kyiv region was liberated from the invader."

CNN could not immediately verify that the entire Kyiv region had been cleared of Russian troops by Ukrainian forces, but the Ukrainian military has in recent days regained control of suburbs around the capital, which has remained under government control. The Russian military has said it is "de-escalating" around Kyiv.

The US is expected to help facilitate the transfer of Soviet-era tanks to Ukraine, according to a source familiar with the plan.

The tanks the US is transferring to Ukraine will be Soviet-era T-72 tanks, which Ukrainian military personnel have experience operating, a senior US official tells CNN.

Those tanks will be delivered “within days, not weeks,” the official said, and will be delivered from NATO partner countries.

Ukrainian President Volodymyr Zelensky has repeatedly asked countries for more tanks.

The New York Times first reported on the transfer.

A total of 4,217 civilians evacuated through corridors in Ukraine on Saturday, according to the country's deputy prime minister, Iryna Vereshchuk.

In a statement on Telegram, Vereshchuk said 1,263 people from the besieged city of Mariupol and the Russian-held city of Berdiansk reached the Ukrainian government-held city of Zaporizhzhia using their own vehicles. 

An evacuation convoy of 10 buses from the city of Berdiansk with more than 300 Mariupol residents also passed Vasylivka en route to Zaporizhzhia, she said. 

Evacuations also continued in Ukraine's eastern Luhansk region, with a total of 2,650 people leaving the cities of Severodonetsk, Rubizhne, Lysychansk, Kreminna, Popasna and Nyzhne, Vereshchuk said. 

Vereshchuk said 17 buses reached the city of Berdiansk from Zaporizhzhia and were expected Sunday morning to continue the evacuation of Mariupol residents. Some of the buses will try to reach closer to Mariupol, she added.

Mariupol, which is ringed by Russian checkpoints, has been under weeks of intense bombardment. Ukrainian officials have described the situation there for the remaining residents as a major humanitarian emergency. 

The International Committee for the Red Cross team that departed Zaporizhzhia on Saturday morning as part of renewed attempt to reach Mariupol, have yet to reach the besieged city, an ICRC spokesperson told CNN.

The team is "spending the night en route to Mariupol and are yet to reach the city," the ICRC spokesperson said.

On Friday evening, the ICRC announced in a statement that its team of three vehicles and nine personnel was unable to reach the city "after arrangements and conditions made it impossible to proceed."