Joe Biden has announced $800m (£613m) in new arms supplies to Ukraineand said he will go to Congress to ask for more funding to help fend off the renewed Russian offensive in the east and south.

Howitzers, artillery and drones among new deliveries, and president to ask Congress for more funding

A Ukrainian service member walks along a trench with a Javelin missile system in the north Kyiv region in mid-March. Photograph: Gleb Garanich/Reuters

The new US weapon deliveries will include 72 howitzers and their towing vehicles along with 144,000 artillery rounds and more than 120 drones tailored for Ukraine’s needs.

“We’re in a critical window of time when [the Russians] are going to set the stage for the next phase of this war,” Biden said. “And the United States and our allies and partners are moving as fast as possible to continue to provide Ukraine the weapons their forces need to defend their nation.”

Fifty Ukrainian artillery officers are being given a week-long course by US instructors on the use of US 155mm howitzers in an unnamed European country, the Pentagon said.

Biden said the latest arms supplies with the emphasis on heavy artillery reflected the requirements of the different landscape of the Donbas, which is largely flat agricultural land, compared with the forests around Kyiv, providing fewer opportunities for ambushes and guerrilla warfare.

The president said the US had so far given Ukraine 10 anti-tank missiles, including Javelins, for every tank Russia has on the battlefield, along with armoured cars, armed drones and other heavy equipment, and was playing the role of facilitator for arms deliveries from other countries.

“We won’t always be able to advertise everything that our partners are doing to support Ukraine in its fight for freedom,” Biden said, and he paraphrased a famous quote of Theodore Roosevelt: “Sometimes we will speak softly and carry a large Javelin.”

The new type of drone the US will deliver to Ukraine is named the Phoenix Ghost and has been developed specifically for Ukraine by the US air force with a California company, Aevex Aerospace.

The Pentagon gave few details about the drone, but a defence department official was quoted by Breaking Defense as saying it was a “one-way drone” that “delivers a punch”, suggesting it is a kamikaze flying bomb similar to the Switchblade drones the US has already delivered.

Ukraine’s president, Volodymyr Zelenskiy, was quick to express gratitude for US “leadership in supporting the people of Ukraine in the fight against Russian aggression”. He said on Twitter: “This help is needed today more than ever! It saves the lives of our defenders of democracy and freedom and brings us closer to restoring peace in Ukraine.”

Zelenskiy was visited in Kyiv on Thursday by the Spanish and Danish prime ministers, Pedro Sánchez and Mette Frederiksen, who pledged new military supplies from their countries. Sánchez promised 200 tonnes of equipment including heavy transport vehicles and ammunition, which he said was Spain’s “largest shipment made until now, more than doubling what we have sent so far.”

Frederiksen said her country would increase the scale of its weapons contribution to Ukraine by 600m Danish krone (£67m).

The new US arms delivery brings Washington’s total military support since the start of the war to more than $3bn. Congress approved a $13.6bn package of military and humanitarian aid in March and Biden said he expected to go back to ask for more next week.

“My hope and my expectation is that Congress would move and act quickly,” he said, thanking Democrats and Republicans for their support for Ukraine funding.

Asked how much he would ask for this time, Biden replied: “That’s being decided now. I’m asking the defence department to put together what they think we need.”

Biden also announced a new $500m disbursement of economic support for Ukraine, a new fast-track route for Ukrainian refugees to come to the US from Europe, and the next step in ratcheting up sanctions on Moscow – a ban on Russian ships visiting US ports.

“That means no ship … that sails under the Russian flag, or that is owned or operated by Russian interests, will be allowed to dock in the United States port or access our shores. None,” he said.

Daniel Tannenbaum, a former US Treasury sanctions compliance official, said enforcing the ban would be challenging. “There has been evidence that they’ve been changing flags over the last few weeks, not sure how much impact this will have,” he said, adding that making the measure effective would require sleuthing into the real ownership of ships sailing under flags of convenience.

The UK in its latest raft of sanctions announced it would ban imports of Russian caviar and other luxury goods, as well as silver and wood products. Tariffs on diamonds and rubber imports from Russia and Belarus will be increased by 35%.

The UK’s international trade secretary, Anne-Marie Trevelyan, said: “We are taking every opportunity we can to ratchet the pressure to isolate the Russian economy and these further measures will tighten the screws, shutting down lucrative avenues of funding for Putin’s war machine.”