Kyiv, May 14 (IANS/DPA): Ukrainian President Volodymyr Zelensky has asked US Secretary of State Antony Blinken for Patriot air defence systems for Kharkiv, which is routinely threatened by Russian missiles.

Two of these systems are necessary to protect Ukraine's second biggest city and its surrounding area, which borders Russia, Zelensky said in Kyiv during Blinken's surprise visit.

US assistance for the campaign against the Russians was of crucial importance, and air defence was the "biggest deficit," Zelensky said.

According to Ukrainian media reports, Blinken promised Ukraine weapons aid that could change the situation on the battlefield.

Blinken said on X: "I returned to Kyiv today to demonstrate our unwavering support for Ukraine as they defend their freedom against Russian aggression."

The visit, which, as usual, was not announced for security reasons, is Blinken's fourth since the start of the war in February 2022 and is also the first visit since the US approved a long-delayed aid package of $61 billion.

Ukraine has been on the defensive for months due to a lack of weapons, ammunition and soldiers.

Russia has been bombarding Kharkiv, and last week Russian troops also began a ground offensive on the border and have already captured several Ukrainian villages.