This was CNBC's live blog tracking developments on the war in Ukraine.

Belarus began military drills on Tuesday in regions along its borders with Ukraine, Lithuania and Poland, the Russian ally's defense ministry said.

The exercises will be held over three days in the Gomel and Grodno regions, and are intended to prepare officers and territorial defense personnel for potential defense of their respective regions, along with practicing protocols in the event martial law is enacted in the country, the defense ministry said on the Telegram messaging app.

Poland and Lithuania are members of both the European Union and NATO.

Russia and Ukraine meanwhile continued to exchange drone strikes in recent days, with Russia on Monday night targeting energy facilities in raids on the Dnipropetrovsk and Kirovograd regions, Ukraine's Operational Command "South" said on Facebook.

The military unit said air defense forces destroyed three drones over Dnipropetrovsk while the rest were intercepted by other units, but an infrastructure target was struck in Kirovograd with no casualties.

Ukraine responded on Tuesday by striking one of Russia's biggest oil refineries in the Tatarstan region, around 800 miles from the front lines, and claimed it had inflicted significant damage on a military target.

Ukraine's Zelenskiy signs bill lowering mobilisation age for combat duty to 25

Ukrainian President Volodymyr Zelenskiy has signed a bill to cut the mobilisation age for combat duty to 25 from 27, the parliament's website showed.

— Reuters

Russia confirms new navy chief after Black Sea attacks

Admiral Alexander Moiseyev was confirmed on Tuesday as the new head of Russia's navy.

Moiseyev took on the role in an acting capacity two weeks ago. Local media reported that his predecessor, Admiral Nikolai Yevmenov, was fired following a series of successful Ukrainian strikes on Russia's fleet in the Black Sea.

While Ukraine does not have its own navy, Kyiv has targeted Russian warships on the Black Sea multiple times since Russia launched its full-scale invasion in 2022, and last month claimed to have destroyed a Russian landing ship.

Russian Defense Minister Sergei Shoigu announced Moiseyev's appointment on a conference call Tuesday, according to a Reuters report. He also presented the appointment of Vice Admiral Konstantin Kabantsov as commander of Russia's Northern Fleet, and Vice Admiral Sergei Pinchuk as commander of the Black Sea fleet.

— Jenni Reid

Russian forces pushing Ukrainian forces westward, defense minister says

Russian Defense Minister Sergei Shoigu on Tuesday said that Russian forces continued to push Ukrainian forces westward, claiming that Moscow's troops had seized control of more than 400 square kilometers (155 square miles) of Ukrainian territory since the start of the year.

"After the failed counteroffensive, the enemy is trying to gain foothold on certain directions and positions, but has not achieved its goals on any of the directions," Shoigu said on a conference call with the leadership of the Russian armed forces, according to an NBC News translation.

"Groups of Russian troops continue to push Ukrainian formations westward," Shoigu said.

CNBC could not independently verify the developments on the ground.

— Sam Meredith

Blinken warns of 'critical moment' for Ukraine

U.S. Secretary of State Antony Blinken on Tuesday warned that Ukraine is at a "critical moment" in the war with Russia and is in urgent need of more Western support, as a multibillion dollar U.S. aid package stays stalled in Congress.

Blinken told journalists during a visit to Paris that it was "absolutely essential" to get Ukraine more military supplies, particularly munitions and air defenses, according to media outlets, including Reuters.

Republicans in the House of Representatives have held up the White House's supplementary budget request for Ukraine, citing other domestic priorities, such as border security.

- Elliot Smith

Putin: Russia will find out who ordered Moscow concert shooting

Russian President Vladimir Putin on Tuesday vowed to find out who ordered last month's mass shooting in a Moscow concert hall, which killed at least 144 people.

"We will definitely get to those who ordered it," Putin told a meeting of Interior Ministry officials, according to Reuters. He also reportedly stressed that the Kremlin's investigation of the incident "must be extremely objective and professional."

Terror group ISIS claimed responsibility for the attack.

Russian spy boss says U.S. intelligence on Moscow terror attack was too general

Sergei Naryshkin, director of Russia's Foreign Intelligence Service, said that intelligence supplied by the U.S. ahead of the deadly terrorist attack on a Moscow theater last month was too general, Russia's Interfax news agency reported on Tuesday.

U.S. intelligence agencies notified Moscow of an imminent assault two weeks before the attack that killed more than 130 people. Terror group ISIS claimed responsibility, but did not provide proof.

- Elliot Smith

Ukraine drone strikes major oil refinery deep into Russian territory

On Tuesday, Ukraine struck one Russia's largest oil refineries with a drone attack on the highly industrialized Tatarstan region, around 800 miles from the front lines of the conflict.

Kyiv also claimed it had inflicted significant damage on a military target, according to Reuters. Rustam Minnikhanov, the head of the Tatarstan regional administration, confirmed in a post on Telegram that industrial locations had been targeted by drone strikes in the towns of Nizhnekamsk and Yelabuga.

"There is no serious damage, the technological process of the enterprises is not disrupted. In Yelabuga, unfortunately, there are victims as a result of the destruction of the premises. They are given all the necessary help," Minnikhanov said, according to a Google translation.

Reuters reported that drones struck a primary refining unit at the Taneco refinery, one of Russia's biggest with a production capacity of around 360,000 barrels per day. Russia's state-owned RIA news agency reported that a fire broke out at the refinery but was extinguished within 20 minutes.

— Elliot Smith

Germany to send 180,000 rounds of artillery shells to Ukraine via Czech ammo initiative - Reuters

Germany will send an additional 180,000 rounds of artillery shells to Ukraine as part of a Czech-led initiative to supply ammunition for Kyiv's war effort, Reuters reported on Tuesday, citing a German defense ministry spokesperson.

CNBC could not independently verify the information.

The shells will reportedly cost Europe's largest economy 576 million euros ($619 million), on top of the separate 478 million euro package announced by Defense Minister Boris Pistorius last month.

- Elliot Smith

U.S. House speaker signals Ukraine aid vote could be imminent

U.S. House Speaker Mike Johnson, R-La., over the weekend indicated that the chamber could soon vote on fresh funding for Ukraine.

Speaking on Fox News on Sunday, Johnson said that "important innovations" to a potential aid package meant that a vote could come soon after Congress returns from Easter recess on April 9.

The speaker faces pressure from within his party by way of House Republican hard-liners in the Freedom Caucus, after he made key concessions in order to pass the recent budget bill and avert a government shutdown.

Many House representatives on the right of the Republican Party have voiced opposition to continued Ukraine aid and have threatened Johnson's position, if he proceeds to bring a Ukraine bill to the floor without ceding to other demands on spending and the border.

The innovations that Johnson mentioned aim to ease some of these concerns, such as including a loan rather than a grant and using confiscated assets from Russian oligarchs to fund the rebuilding of Ukraine.

- Elliot Smith

Belarus starts military drills near Ukraine, EU borders

Belarus began military drills on Tuesday in regions along its border with Ukraine, with European Union nations Lithuania and Poland, the Russian ally's defense ministry said.

The exercises will be held over three days in the Gomel and Grodno regions, and are intended to prepare officers and territorial defense personnel for defense of their respective regions, along with practicing protocols in the event that martial law is enacted in the country, the defense ministry said on the Telegram messaging app.

It also highlighted that April 2 is the "Day of Unity" for Belarus and Russia, commemorating the "long-term friendship of the peoples of Belarus and Russia," according to a Google translation.

"The armies of Belarus and Russia regularly conduct joint military exercises and stand shoulder to shoulder to protect peace and security," the defense ministry added.

— Elliot Smith

Russia targets energy infrastructure in overnight drone strikes, Ukraine says

On Monday night, Russia targeted various energy facilities in drone strikes on the Dnipropetrovsk and Kirovograd regions, Ukraine's Operational Command "South" said on Facebook on Tuesday.

The military unit said air defense forces destroyed three drones over Dnipropetrovsk, while the rest were intercepted by other units, but an infrastructure target was struck in Kirovograd with no casualties.

— Elliot Smith

Zelenskyy holds talks with officials over Ukrainian drone production programs

Ukrainian President Volodymyr Zelenskyy held talks on Monday with military and government officials over Kyiv's drone production plans and a project to build an "integrated electronic warfare control system" to protect Ukrainian troops from Russian drone attacks.

"We revised and specified production plans for all types of drones this year, including FPV, bombers, reconnaissance, and long-range drones for special missions," the president said in a post on X.

"We discussed how to ensure our defense industry's flexibility. Frontline needs are constantly changing, and our manufacturers must respond in a timely manner."

He added that "important decisions were made to streamline procurement procedures and component imports, increase the production of charges for drones, and train operators."

— Elliot Smith

Ukraine's national grid chief says energy system collapse unlikely despite Russian strikes

The head of Ukraine's national grid company said on Monday that while Russian drone attacks have significantly damaged the Ukrainian power system, a total collapse is unlikely.

Russian forces have been attacking thermal and hydropower stations on a regular basis since March 22, causing blackouts in many regions.

"Their [the Russians'] goal is to impose blackouts in some major Ukrainian cities, and our goal is to prevent it," Ukrenergo chairman Volodymyr Kudrytskyi told Reuters in an interview.

— Elliot Smith

Read CNBC's previous live coverage here:

Putin says NATO won't be attacked but F-16s will; Kyiv claims Russia knew terror attack was coming