Joe Biden Arseniy Yatsenyuk
U.S. Vice President Joe Biden shakes hands with Ukrainian Prime Minister Arseniy YatsenyukReuters

The United States is set to boost non-lethal aid deliveries to Ukraine's government, but will not send weapons at the current time, according to Reuters news agency.

Washington has long debated the merits of boosting weapons deliveries to Ukraine, although it has failed to do so to date, amid fears that such a move could push Moscow to boost its own supplies to the pro-Russian separatists.

Citing unnamed US officials, Reuters said the non-lethal aid deal is expected to be announced during US Vice President Joe Biden's visit to Kiev, where he arrived on Thursday (20 November).

The officials are reported as saying the aid would include Humvee vehicles and would expand support for Ukraine's armed forces, although it would probably not alter the conflict significantly.

The aid would include a delivery of Humvees and radars designed to detect the position of enemy mortar, the officials said, without placing a monetary value on the assistance.

The agreement falls short of Ukrainian President Petro Poroshenko's calls for lethal aid deliveries from the US.

Russia had warned the US not to send weapons to Kiev on Thursday, after a senior official said the administration was considering sending lethal assistance to Ukraine.

More than 4,300 people have been killed in eastern Ukraine since fighting erupted in April 2014 between separatist rebels and government forces.

Western powers have accused Russia of supplying the rebels with weapons and manpower, while Moscow has denied backing the rebels.